As Raj is walking up the stairs with Leonard and Howard, he suggests 48 hours of online Star Wars gaming, starting Saturday morning. 48 hours from Saturday morning would be Monday morning, meaning the guys would all be at Sheldon and Leonard's apartment going to work.
Stuart offers Sheldon Excalibur as a gift for Amy's aunt to use as a cane. In The Russian Rocket Reaction (2011) Sheldon and Leonard are considering buying Longclaw (Jon Snow's sword from Game of Thrones (2011)), but Sheldon is not sure if it's the right sword to start their sword collection. Leonard asks what sword he wants and Sheldon says Excalibur. Leonard said Stuart didn't have Excalibur.
While playing SWTOR Leonard tells Raj the Empire is on his tail, indicating they are playing Republic characters, which is further supported by the view of Raj's laptop. However, the screen shot of Bernadette's character clearly shows she is playing a Sith Inquisitor (armor in SWTOR is specific to both class and faction).
Sheldon says he is going to run around outside with a wet head and try to catch a cold. He should know that a wet head has nothing to do with catching colds.
At 5:11 in Kaley Cuoco looks right at the camera for a split second.
While playing the drinking game with Amy, Penny says "Now I will drink this entire cup of beer" but you can tell all three cups are only half full.
Sheldon is heard saying 'Legos' even though 'Legos' is wrong. According to The Lego Group itself the proper usage is 'Lego bricks', 'Lego pieces', 'Lego sets' etc. Never 'Legos'.