When Jonah Bobo's character, Robbie, is deleting Jessica's number from his cellphone you can read that another contact in his phone is 'Joey K'. Joey King is the name of the actress playing Molly, his sister on screen.
The cocktail that Jacob drinks and makes throughout the movie is an "Old Fashioned," considered by some historians to be the first American cocktail. The recipe usually included sugar and bitters muddled together, club soda and ice, rye whisky, and a large slice of orange peel.
The golden round shaped symbol that Kate (Marisa Tomei) is wearing in the scene when Cal (Steve Carell) hits on her actually refers to a married women in the Indian tradition, although she is single here.
The trivia item below may give away important plot points.
Marisa Tomei's character is revealed to be Robbie's English teacher when she first meets Cal at the bar, as she is wearing the same watch and bracelet seen when she writes on the blackboard earlier in the film.