That on-screen chemistry you witnessed between Leonard and Penny wasn't just brilliant acting — it was actually very real! Kaley Cuoco and Johnny Galecki secretly dated for two years, and not even their cast mates knew about the secret romance!
There was a Belarus edition of The Big Bang Theory called The Theorists. It was pretty much the exact same show. The actors of The Theorists quit when they realized that the show's producers had totally ripped off an American TV show.
Both Mayim Bialik and Kaley Cuoco had to hide injuries while filming. A horseback riding accident left Cuoco with a broken leg, and she had to film her scenes while standing behind a counter. Bialik also had to hide an arm injury during filming.
One thing is for sure: this cast is dedicated to the authenticity of their characters. So dedicated, in fact, that several of them have learned to play instruments that their characters play. Bialik, for instance, took up the harp when she learned that it was Amy's instrument of choice and Parsons learned how to play the theremin.
Apparently, Leonard was originally a much more dapper character. In the original pilot he only wore suits, but fortunately the writers changed his go-to attire to casual, comfy hoodies, which makes so much more sense. Hoodies are so Leonard.
The Big Bang’s co-creator Bill Prady first heard “Soft Kitty” at his daughter’s pre-school. He loved the song so much that he decided to use it in the show, assuming it was public domain. However, the show was sued in 2015 by the family of Edith Newlin, who wrote the 1937 song, “Warm Kitty.” The lyrics are a little too close for comfort.