The production was shot without a completed script. As a result, there were many delays and arguments over what to shoot. James Gandolfini admitted, in a behind the scenes interview, that most of the film was "improvised".
The original Christmas 2003 release date was pushed back ten months, to avoid competing with another Ben Affleck film, Paycheck (2003). Because of this, there's a 2003 calendar hanging in Brian's bedroom, near the door.
James Gandolfini was only ten years older than Christina Applegate, who played his daughter in this film.
John Wight, who was Ben Affleck's stand-in , wrote a devastating depiction of what the filming was like in his book "Dreams that Die: Misadventures in Hollywood".
Filming did not take place in Arlington Heights, Illinois (a suburb of Chicago) because the weather was too cold.