Continuity mistake: When Gigi calls Alex for the first time to get his opinion about a guy "Jarrad", Alex puts her on hold and goes into his office to pick up the call. In the bar the phone line is lit up where it's holding, but the office phone is not lit up at all.
Character mistake: About 3/4 of the way through the movie, when Jennifer Aniston is talking to Ben Affleck, she calls him Ben instead of his character's name Neil.