Visible crew/equipment: After Matt finds out that Nicole is engaged, he goes running through the streets. When he goes running past a glassed store display, you can see the reflection of a white van with the sliding passenger door open and a cameraman. (00:14:00)
Continuity mistake: In the scene where Josh Hartnett is about to break his vow in the bathroom, he opens the window and jumps out. In the shot of people looking at Jerry, the window is closed when no one touches it. (01:00:40)
Factual error: Josh Hartnett's roommate is reading the paper, which shows results from a big football game. But this movie is set during Lent, months away from football season. (The filmmakers admit this error during the DVD commentary.).