In "The Agreement Dissection", Sheldon says to Leonard that he hates Greek food and Leonard answers "Not as much as you" which is a confusion quote because it refers to 2 phrases: "Not as much as I hate you" and "Not as much as you do".
Season 8[]
In "The Intimacy Acceleration" Penny discovers it is Sheldon's birthday. She responds with “I never took you for a Pisces”. This contradicts the episode in season 1 “the peanut reaction” where after an argument between Sheldon and Penny she says “you are a typical Taurus”.
In "The Maternal Combustion", Amy was absent during the visit of Leonard and Sheldon's mothers Beverly Hofstadter and Mary Cooper. This was because her portrayer Mayim Bialik had to take some time off to be with her family following her father's death that had happened recently. The plot hole here is that since she is absent, it is unexplained and unknown where she is and why she could not be there and Mary doesn't even ask Sheldon about her and Amy doesn't even tell Leonard, Sheldon and Penny why she can't be there during the visit of the mothers. Also Beverly asksLeonard, where Mary is from and after Leonard answers "East Texas" Beverly is annoyed, this is at first a plot hole because she should know where Sheldon is from since they know each other really good, also she actually likes Sheldon who is also from Texas.
Inconsistency[]
Plot points in The Big Bang Theory story lines where facts do not agree with past points. Here is the list below:
1. In "The Dumpling Paradox" (Season 1 Episode 7), the boys start Halo night 6 minutes late, and determine if the 6 minutes should be taken out of game time, bathroom time, or pizza break. Wednesday is Halo night, so it must have been Wednesday. But pizza night is on Thursday.
Sheldon caught in an electrified net in The Bozeman Reaction
5. Sheldon says that Amy doesn't like to wear costumes in "The Justice League Recombination" (Season 4 Episode 11). However, she does dress as a pretzel, a Star Fleet medical officer, Snow White and more in various episodes. She wore the Star Fleet medical officer outfit for Sheldon to like her more and the pretzel as a part of Sheldon's web show "Fun with Flags". The greatest counterexample is in "The Holographic Excitation" (Season 6 Episode 7) when she asks Sheldon to join her in a couple's costume pair.
6. In "The Thanksgiving Decoupling" (Season 7 Episode 9) and "The Proton Transmogrification (Season 7 Episode 22), Sheldon says that his father died when he was 14 years old. However, in "The Pancake Batter Anomaly" (Season 1 Episode 11), Sheldon states that he was once sick in Germany when he was 15 years old, and his mother wasn't able to fly to take care of him because she needed to help his father as the house had been damaged in a tornado.
Also, Sheldon mentions that his father tried to give him a beer for his high school graduation, but he was 11 and his mom said no. This creates a mistake as Sheldon never attended high school and instead started college right after leaving elementary school. But in Young Sheldon, Sheldon does attend high school when he was 10 and graduated when he was 11.
7. The famous flashback episode, "The Staircase Implementation" (Season 3 Episode 22), details Leonard moving into Sheldon's apartment seven years prior to the episode, putting the events of the flashback in May 2003. However, in "The Stag Convergence" (Season 5 Episode 22), when Sheldon is comforting Howard, he says, "Also, there was a single cube of chicken bouillon in the cupboard when I moved in and it’s been bothering me for the last eight years. So, as they say, two birds." The Stag Convergence took place in May 2012, making Sheldon's reference of him moving into the apartment eight years ago at 2004, a year after Leonard is supposed to have moved in. Theoretically, one could claim the cube of chicken bouillon did not bother Sheldon for a full year after he moved in but that seems unlikely for our lovable Sheldon Cooper.
8. Rajesh says that he doesn't know how to speak Hindi when he encourages Sheldon to learn the language when Sheldon wants to be intellectually stimulated. However, in the earlier episodes Rajesh can be seen speaking Hindi, watching Hindi movies.
9. When Howard and Bernadette decide to get married before he leaves for space in "The Decoupling Fluctuation" (Season 6 Episode 2), the group looks for venues where they can get married. Howard suggests Vegas, but Bernadette shoots him down saying "isn't that tacky". Penny replies "I know tons of people who got married in Vegas", this suggests that she knows that people who get married in Vegas are really married. However, in "The Leftover Thermalization" (Season 8 Episode 18), Penny says that she married Zac as a goof and she thought that the Vegas marriages are not real marriages.
10. In an early episode when the guys kick Sheldon from the Physics Bowl team and they are looking for a fourth player Raj mentions two actresses that are really smart, that actually later appear in rolls on the show. He refers to the girl who plays TV's blossom (Maiam Bialik who plays Amy and is a neuroscientist in real life) and he says the girl from The wonder years (Danika Mckellar who is a best selling author in mathematics). Danika goes on to play a grad student I believe at a mixer and gets together with Raj.
Throughout some episodes of The Big Bang Theory, there have been some contradictions, which include the following:
Sheldon is sarcastic to Leonard, telling him that "Archimedes would be so proud" in the "The Big Bran Hypothesis" (Season 1 Episode 2) when Leonard fails after invoking the mathematician's name and teachings. In the following episode, "The Fuzzy Boots Corollary," however, it is made apparent several times that Sheldon does not understand sarcasm and even needs a SARCASM sign. It may possibly be that Sheldon knows what sarcasm is, but he can't tell when other people are using it.
Sheldon with the cats.
In "The Fuzzy Boots Corollary", Leonard mentions Sheldon gets asthma when he is around cats. In "The Griffin Equivalency" (Season 2 Episode 4), Sheldon said that his family had a pet cat named Lucky. In "The Zazzy Substitution" (Season 4 Episode 3), Sheldon buys 25 cats when Amy "broke up" with him. He could take medication for it, which is what many people do.
In "The Maternal Congruence" (Season 3 Episode 11), Sheldon cheers for the Grinch's meanness and finds it a buzzkill when he succumbs to social convention and gives the presents back. In a different episode, Sheldon compares Stuart to the Grinch in a bad way, demonstrating he knows of the negative connotations of the Grinch.
Early in season 1 - "The Luminous Fish Effect" (Episode 4) - Sheldon tells Penny that he is 140 pounds when he goes to the market with her. However, near the end of season 1 - "The Porkchop Indeterminacy" (Episode 15) - he tells his sister, Missy, to tell their mother that he is 165 pounds, which would be a 25-pound increase in only a few months. It's possible this was just lip service to keep his mother off his back.
In "The Luminous Fish Effect" (Season 1 Episode 4), Sheldon estimates that the car he and Penny are riding in is about 4000 pounds. This cannot be correct, as it is a Volkswagen Rabbit (Golf Mk 1) and would be approximately 2000 pounds, maximum.
In the "The 21-Second Excitation" (Season 4 Episode 8), Sheldon recalls how he made Leonard wait in line for Star Trek: Nemesis to get good seats, though that film was released in 2002 and Leonard and Sheldon didn't meet until 2003, according to the flashback episode, "The Staircase Implementation" (Season 3 Episode 22). Given the tepid response to the film by the public at large, it's unlikely there was a revival showing of it, unless it too had unseen footage that would have made the movie better.
In "The Luminous Fish Effect" (Season 1 Episode 4), Sheldon gave a complicated explanation of what he did with his life past fifth grade, which combined would make him 23 at that time. However, in "The Friendship Contraction" (Season 5 Episode 15), Leonard stated that Sheldon was 30. Given the information in "The Luminous Fish Effect", Sheldon would only be 27 in "The Friendship Contraction."
Amy's name tent does not have "Dr" on it, unlike Raj's, despite both having PhDs.
In "The Love Car Displacement" (Season 4 Episode 13), Amy's name tent did not have the title "Dr" in front of her name, while Sheldon's, Leonard's, and Rajesh Koothrappali's did. Obviously Howard's didn't. This is a contradiction manifested as a prop error because the show later reveals Amy does, in fact, have a doctorate.
In "The Good Guy Fluctuation" (Season 5 Episode 7), Stuart congratulates Leonard for being the first person to pick up a girl in Stuart's comic book store. However, Stuart himself picked up a girl (Penny) in the comic book store in season 2 (Episode 20: "The Hofstadter Isotope").
In "The Pancake Batter Anomaly " (Season 1 Episode 11), Sheldon tells Penny that he once got sick alone in Germany when he was 15 years old and because his mother had to fly back to Texas to help his dad. This clearly suggests Sheldon's dad was alive when he was 15. However, in "The Thanksgiving Decoupling" (Season 7 Episode 9) and "The Proton Transmogrification" (Season 7 Episode 22), Sheldon tells Bernadette's father Mike Rostenkowski and Professor Proton, respectively, that his father died when he was 14.
In "The Gothowitz Deviation" (Season 3 Episode 3), Sheldon told Penny he doesn't dance, even in an infinite number of universes. However, in "The Agreement Dissection" (Season 4 Episode 21), Sheldon said he's an excellent dancer. Sheldon proves that later in the episode when skillfully dancing with Amy. It is also well established before this in "The Fuzzy Boots Corollary" (Season 1 Episode 3) and "The Middle-Earth Paradigm" (Season 1 Episode 6) that the boys do not like dancing. However, this could be Sheldon warming up to the girls, especially Amy.
Sheldon makes a categorical error in "The Bat Jar Conjecture" (Season 1 Episode 13). When Howard says he should answer the engineering questions because he is an engineer, Sheldon compares this to him answering all of the anthropology questions because he is a mammal. Anthropology is the study of humans, not mammals; all humans are mammals, but not all mammals are humans. He ought to have said mammalogy, or claimed he was a human.
In "The Killer Robot Instability" (Season 2 Episode 12), Sheldon and the guys want to improve their fighting robot, but Sheldon doesn't even know how to open the tool box, which implies he has no mechanical skills. Sheldon claims that while he grew up in Texas he built a CAT scanner out of his sister's EasyBake Oven, a sonic death ray, and tried to build a nuclear reactor, thus having some skills to invent things.
In "The Roommate Transmogrification" (Season 4 Episode 24), Bernadette turns down the heart disease project because neither of them have heart problems. In the previous episode, "The Engagement Reaction", Howard claims that his family is the history of heart disease after his mother is sent to the hospital.
This is more of a fallacy and not so much of a contradiction, but in "The Euclid Alternative" (Season 2 Episode 5), when Sheldon asks Howard to change the color of the car in the simulator he says, "You know the pale blue of Luke Skywalker’s lightsaber, before it was digitally remastered?" Luke Skywalker's lightsaber is green, as is demonstrated in Episode VI: Return of the Jedi, because he built it. The pale blue lightsaber he uses in Episodes IV and V is his father's, Anakin Skywalker's.
The famous flashback episode, "The Staircase Implementation" (Season 3 Episode 22), details Leonard moving into Sheldon's apartment seven years prior to the episode, putting the events of the flashback in May 2003. However, in "The Stag Convergence" (Season 5 Episode 22), when Sheldon is comforting Howard, he says, "Also, there was a single cube of chicken bouillon in the cupboard when I moved in and it’s been bothering me for the last eight years. So, as they say, two birds." The events of "The Stag Convergence" took place in May 2012, making Sheldon's reference of him moving into the apartment eight years ago at 2004, a year after Leonard is supposed to have moved in. Theoretically, one could claim the cube of chicken bouillon did not bother Sheldon for a full year after he moved in but that seems unlikely for our lovable Sheldon Cooper.
In "The Codpiece Topology" (Season 2 Episode 2), Leonard struggles to find examples of his previous girlfriends beyond Joyce Kim and Leslie Winkle. However, in the previous episode, "The Bad Fish Paradigm," Sheldon tells Penny that Leonard used to date a woman with a PhD in French literature. Unless Joyce Kim has a PhD in French literature, which would be another contradiction given it was stated the girl with a PhD in French literature was French herself, Leonard totally forgot a girlfriend.
In "The Adhesive Duck Deficiency" (Season 3 Episode 8), when Sheldon is driving Penny to the hospital, he becomes distressed that Penny's car's check engine light is on. This is a double contradiction/inconsistency. Previously, in "The Financial Permeability" (Season 2 Episode 14), when Penny is explaining how she got behind on her bills due to her car breaking down, she said, "Well the check engine light is fine. It’s still blinking away. It’s the stupid engine that stopped working. It cost me like twelve hundred dollars to fix it." The period between "The Financial Permeability" and "The Adhesive Duck Deficiency" is nine months. Unless Penny did some serious harm to her car in that time period, her engine should have been fine from fixing it in "The Financial Permeability". However, even before "The Financial Permeability," it is first established Sheldon learns of her check engine light in "The Euclid Alternative" (Season 2 Episode 5). So Sheldon should have already been used to Penny disregarding practical vehicular maintenance.
In the beginning of "The Romance Resonance" (Season 7 Episode 6), Sheldon is "in the zone" at The Cheesecake Factory. When Penny asks what he's doing, Amy responds with, "Could be anything. Last time he was like this, he figured out electron transport in graphene. The time before that, he was making a list of who’s allowed in his tree fort if he ever gets one. Still can’t believe I didn’t make the cut." This can't be true because the first event Amy is referencing occurs in "The Einstein Approximation" (Season 3 Episode 14). Sheldon is stuck on a problem which he describes as, "Trying to figure out why electrons behave as if they have no mass when traveling through a graphene sheet." Sheldon hadn't even met Amy by "The Einstein Approximation," so claiming Sheldon excluded Amy from his approved tree fort guest list is fallacious. The only justification to make it logical is that he first created the list before meeting Amy, periodically edits it, and excluded Amy up to that point.
In "The Engagement Reaction" (Season 4, Episode 23), Sheldon refuses to go to the hospital, where Howard and his mother have been taken, because of all the germs. But only one season earlier, Series 3 Episode 08 – The Adhesive Duck Deficiency, Sheldon had taken Penny to the Emergency Room with no such concerns.
In "The Einstein Approximation" (Season 3, Episode 14), Sheldon wakes up Penny and Leonard, mentioning that the snoring was worse when Penny was on her back. Penny thinking that Sheldon was referring to Leonard, said that Leonard does not snore. However, in "The Septum Deviation" (Season 8, Episode 9), Leonard had been snoring for years and Sheldon had gotten used to it.
In “The Cushion Saturation” (Season 2 Episode 16), Sheldon can't eat in his spot because Penny ruined the cushion. After Leonard told him to sit and eat in his desk chair, Sheldon tells everyone, that he does not eat where he works and does not work where he eats. But previously in "The Cooper-Nowitzki Theorem" (Season 2 Episode 6) we can see Sheldon sitting in his spot working with his laptop while Ramona is doing his toenails.
In "The Celebration Experimentation", Penny mentioned Beverly didn't know about their Vegas wedding, which was fine with Beverly. In "The Line Substitution Solution" when Penny asks if Beverly knows what an insult is, Beverly then tells Penny says she felt insulted that she wasn't invited to her son's wedding nor even being told that it was taking place.
In S1E4, Sheldon gives a history of his life. He claims to have started college at age 11 after 5th grade, graduated at age 14, and got his PHD at age 16. This is contradicted several times, most notably him skipping from fifth grade to college. At the start of Young Sheldon, Sheldon is 9 and starting high school. The previous year he was in the same grade as his twin sister, implying he skipped from third to ninth grade.
In S3E6, Sheldon claims he watched football with his dad from the time he was 5 until college, the longest 7 years of his life. Sheldon started college when he was 11, so it should've only been six years.
In {ad episode} when they dress up as the Justice League, Penny asks why Amy can't be Wonder Woman, and Sheldon replies that Amy doesn't do dressing up. However, throughout the series, Amy dresses up as a Star Trek nurse, a Disney princess and also wanted to do a couples costume for Halloween.
In S6E2, when Howard and Bernadette decide to get married before he leaves for space, the group looks for venues where they can get married. Howard suggests Vegas but Bernadette shoots him down saying "isn't that tacky". Penny replies "I know tons of people who got married in Vegas," this suggests that she knows that people who get married in Vegas are really married. However, in S8E18 "The leftover Thermalization", Penny says that she married Zac as a goof and she thought that the Vegas marriages are not real marriages.
When Sheldon wants to be intellectually stimulated, Raj suggests for him to learn Hindi to which Sheldon responds that he already knows the language. After Sheldon (poorly) says something in Hindi, Raj asks him to translate as he has never learnt Hindi. However, in various episodes, Raj can be seen speaking Hindi and even watching a film in the language.
According to "The Staircase Implementation", the gang met when they were all working at the university in 2003. At the time, they would have all been 22-23 and would not have PhDs unless they skipped a few years of school. This is unlikely,for everyone but Sheldon. In another episode, Leonard even says he got his PhD at age 24, which would be in 2004.
In S1E14, it is mentioned that the elevator has been broken for two years, which would be in 2006. According to S3E22, the elevator is revealed to have been broken in 2003.
In S2E3, Penny claims she hasn't had sex in six months. She clearly had sex with that other guy the night before she went out with Leonard, which was after Leonard's birthday, likely in May. This means, S2E3 would have to take place in at least November, despite airing in early October.
In S5E1, Leonard says he dated Priya for 8 months. Assuming the show runs relatively on real time, they only dated for 3 months (February - May) before Priya moved back to India. Even if S4E24 takes place in September, it would still have been only 7 months, as she moved back to India a while before Halloween.
Sheldon and Amy can never agree on when their relationship started. While they knew each other a year and a half before officially dating, most of the time they acknowledge that they have been dating since the season 3 finale. However, in late season 7 and early season 8 they claim to have been together for 3 years.
Bernadette was pregnant with Halley for about 44 weeks (February 15 - December 17). It is later mentioned that Halley was born 2 weeks late, but the math calculation would indicate she would've born 4 weeks late.
In S8E12, Sheldon reveals that Amy taught him how to drive. However, in S10E16, he reveals to Amy that he knows how to drive and she is surprised.
Penny and Bernadette met Amy at the Cheesecake Factory in S11E9, yet they do not recognize her when they officially meet her months later.
In the season 3 finale, when Amy meets Sheldon, she claims to only go on one date a year. However, in S11E9, it is shown that Amy was on a date very recently before meeting Sheldon, as it was after Penny and Bernedette broke up with Leonard and Howard.
