Continuity mistake: When Frank returns home from the Lynskeys, he parks his Volvo right beside the outdoor fuse box post, with the box facing beyond the trunk of the car. However, after Frank goes upstairs, in the next exterior aerial shot the Volvo is 10-15 ft. away from the fuse box post and the box now faces beyond the front of the car.
Continuity mistake: The colours on the dial of the freezer Frank goes in changes between shots. When Lucy turns it down you can see the colours are light and dark blue. Later on in the wider shots and when she tries to open the door and Milton Dammers stops her, you can see it's blue and red.
Trivia: When Frank comes out of the newspaper building, he walks into a guy with piercings and t-shirt with the Grim Reaper on it, this is the Director, Peter Jackson, he does a Hitchcock in all his films.