The word processor file in which Mavis composes her novel throughout the film is titled "pieceofshit.doc".
Charlize Theron was Jason Reitman's first and only choice for the lead role.
The story was inspired by an article Diablo Cody read about a woman who decided to pursue her high school sweetheart years later. While the article had a happy ending, Cody thought to herself, "What if it didn't?"
When they were casting the movie, Jason Reitman asked Diablo Cody what she thought about Patton Oswalt for the role of Matt, and if the writer knew the actor's work. Cody replied deadpan: "Are you serious?" This, of course, because Oswalt was a semi-regular actor on Cody's television show, United States of Tara (2009).
The crew had difficulty finding a Mini with a tape deck, so they had to jerry-rig one in the car they got.