Howard mentions Bale personified the words "I am Batman". These words were ad-libbed by Micheal Keaton who was supposed to say "I am the night". Tim Burton kept the sentence as he liked it more than the scripted one, meaning Bale just reused it.
Sheldon mentions he is a fan of "Tibetan" throat singing, which doesn't exist. He probably meant Tuvan throat singing, which does and which he demonstrated in season 3, episode 15 "The Large Hadron Collision."
Several guests arrive for Sheldon's birthday party: Leslie Winkle, Barry Kripke, Wil Wheaton and Leonard's mom. It would seem logical that Sheldon's own mother should have been there.
Most likely Sheldon's mother was with Missy - Sheldon's twin sister.
Most likely Sheldon's mother was with Missy - Sheldon's twin sister.