Plot Holes

In "The Big Bang Theory", there have been some plot holes which can be found in "Contradictions" and "Inconsistencies", but here are plot holes.

Plot Holes

 * 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.