Factual error: Gino commits a murder using a six-shooter with a silencer attached, and his shot doesn't make any noise. But it should have. Though it's a long-standing Hollywood cliché, a revolver with a silencer wouldn't be silent at all. Unlike automatic weapons, revolvers are open-chambered, which allows sound to escape. They can't be muffled with a silencer.
Continuity mistake: When Mundy and Claire are sitting in the car outside the apartment building, the rear view mirror has disappeared (probably removed to prevent it from obscuring the actors' faces). It mysteriously reappears later on.