Ben Affleck signed onto the film with the belief that it'd support his brother Casey Affleck in his first leading role while he played a small uncredited role. He was surprised to see his name in the trades as a headline for signing onto the film.
During filming Casey Affleck mentioned to Kate Hudson that 'Romeo and Juliet' by Dire Straits was one of his favorite love songs. Hudson secretly convinced the director to play the song during Affleck and Hudson's characters final scene together as a surprise for him. Casey Affleck didn't find out until he watched the movie at the premiere.
This movie is set during New Years in the dead of winter, yet there is no snow, the people's breath is not visible, and people are not dressed at all for winter weather.
When Caitlyn and Bridget are talking to the bartender (when he tells them he's a law student) Bridget's straps switch from on her shoulders and off her shoulders.
Jack: Look, what happened between us last night is like this ongoing problem with me. It happens all the time: I meet someone, we go home together, but then the next day it's...
Disco Cabbie: One of the ugliest bitches I've ever seen in my life rolled up, and I'm not one to call women ugly, but I think this woman was, because she had a penis.