'The Big Bang Theory' trivia and fun facts

Floors two, three, and four of Sheldon and Leonard's apartment building are the same set just re-dressed for each scene. This can be seen in the fact that the scuff marks on the moulding are identical on each level as they walk up the stairs.

Most of the time, Leonard has no lenses in his glasses.

Raj's inability to talk to women except when drunk is based on an old co-worker of executive producer Bill Prady when he worked at a computer company.

Jim Parsons audition for the role of Dr. Sheldon Cooper was so good that creator Chuck Lorre immediately asked Parsons to come in for a second one, because Lorre wanted to be 100% sure Parsons was as brilliant as he seemed.

Mayim Bialik is the only cast member to have a PhD. In 2008, she completed her neuroscience studies. She earned her Ph.D. in Neural Biology.

Despite the fact that some viewers take Sheldon's behavior, mannerisms, and social skills as a sign that Sheldon has Asperger's syndrome or otherwise falls on the autism spectrum, the show-runners have persistently denied in many interviews that Sheldon has Asperger's or any other type of autism. It should be noted however, that actor Jim Parsons has stated that he does think that Sheldon actually does have Asperger's syndrome and portrays him as such.