At the end of the movie, when Vincent closes the trunk of the Cadillac Deville with his leg, there is a distinctive latching sound of the trunk. Cadillacs do not make such a sound since they have a motorized trunk-closing mechanism which closes the trunk silently when the deck lid is closed gently. It is impossible for a Cadillac to make such a sound as the one in the movie (unless it was modified).
Near the end, when Emily drives the Cadillac into the parking garage, she parks leaving the front wheels turned. Moments later, as she and Vincent are sitting in the trunk, the wheels of the car are pointed straight.