Behind Wil Wheaton, a model of a Star Wars speeder bike with scout trooper figure is visible. This reflects Wheaton's enthusiasm for the Star Wars franchise, which predates his role on Star Trek, and counters his taunt of the Star Wars moviegoers in The Opening Night Excitation (2015).
Bernadette is put on bed rest due to her pregnancy. This was probably done to give Melissa Rauch some rest as well, as she was almost seven months pregnant in real life.
With this being the 237th episode, the show has surpassed Friends (1994) which ran 236 episodes. It would later surpass Two and a Half Men (2003) (262 episodes) and Frasier (1993) (264 episodes) as well. The Big Bang Theory has since been surpassed by It's Always Sunny in Philadelphia as the longest-running live-action sitcom.
Sheldon asks Wil Wheaton if he can contact Patrick Stewart to be his acting coach. Sheldon is obviously ignoring the fact that in The Long Distance Dissonance (2017), he had a letter from Stewart threatening to release his dogs on him if Sheldon would ever come to his house again.