Revealing mistake: In the scene where unit 91 is calling in the Spurbury Police car, it is obvious the car's ignition is not turned on.
Revealing mistake: At 46 minutes into the movie, Foster is outside of the Spurbury police station flashing Ursula. Ursula comes outside with a shotgun and voice changer to surprise him. You hear the pump-action of the shotgun, her voice through the voice-changer, and see the barrel of the shotgun come onto the scene all within about a second. She couldn't possibly chamber the shotgun, hold the shotgun, and hold the voice changer all at the same time without having three hands.