Although having made several prior appearances on the show, this is the first time that Brian George as Raj's father appears on screen with the other characters and not via web cam.
The game that Amy has them play - blowing a ball of wool on a table, with the goal of blowing it off the opponents end - was actually a Victorian era game. Her game 'Hot Boiled Beans' is also from that time, possibly even older.
This episode was inspired by the Breaking Bad (2008) episode, 'Fly', where Walter White and Jesse Pinkman are trying to get a fly out of the lab. Even some of angles of the shots are similar.
Dakin Matthews also played Santa in the season six Christmas episode The Santa Simulation (2012), where he appeared in Sheldon's nightmare, angry about the fact that Sheldon didn't rescue him in his Dungeons and Dragons game.
Sheldon asks Amy if she wishes she were Jewish. Mayim Bialik, the actress who plays Amy, is in fact Jewish.