In the car Sheldon tells Penny that it would be his first date, since square-dancing with his sister at a Teens for Jesus Fourth of July Hoedown doesn't count as a date. However, in The Psychic Vortex (2010), when Raj asks him to meet Abby and Martha for the second time, Sheldon says "Hulk agree to second date with puny humans!"
At 5:49 in Kaley Cuoco looks right at the camera for a split second.
At 17:03 in the man behind Penny in the restaurant looks right at the camera for a split second.
Raj likens Howard's problem to Winnie the Pooh being stuck in the honey tree. In the story by A.A. Milne however, Winnie the Pooh actually gets stuck in the entrance to Rabbit's burrow.