Continuity mistake: At the end of the movie when Sidney is lying on the floor, Roman is pointing the gun to her head about to kill her. The gun is clearly pointing to her head/neck area when he shoots, but Sidney still lives and shows him she was wearing the vest. The vest protects her chest and Roman shot her in the head.
Continuity mistake: In the scene where Dewey and Gale are having lunch, Dewey asks her "Why would the police come to you?" In the background, a waitress in white walks by. Then they switch to Gale and the waitress has vanished.