Talk:The Celebration Experimentation/@comment-207.242.5.126-20160226203440/@comment-27821881-20160229131348

Just a guess but likely Laurie Metcalf couldn't make it to reprise her role as Sheldon's mom due to scheduling conflicts and they wanted to fill in the ...quota for the guest spots? Is there such a thing? Plus, as Physicsisphun! indicated, there's also the novelty of having two actresses on who were Johnny Galecki's former on-screen and off-screen girlfriends, which in a way makes for great discussions and trivia.