Laurie Metcalf, who plays Sheldon's mother Mary Cooper, is the mother of Zoe Perry, who plays Sheldon's mother Mary Cooper on Young Sheldon (2017).
Unlike most TV shows or movies, when characters in the show eat, the prop food is real. Their prop master previously aspired to be a chef and lovingly cooks every meal seen on screen.
Sheldon (Jim Parsons) can be seen wearing various versions of "Flash" t-shirts throughout the series. In the series The Flash (2014), character Cisco Ramon (Carlos Valdes) frequently wears "The Big Bang Theory" based shirts, such as one with Sheldon's catchphrase "Bazinga!"
Jim Parsons's audition for the role of Dr. Sheldon Cooper was so good that creator Chuck Lorre immediately asked him to come in for a second one, because Lorre wanted to be one hundred percent sure Parsons was as brilliant as he seemed. After the second audition went perfectly, Lorre cast him on the spot.