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.