When the Decepticon police car transforms and chases Sam under the freeway (at about 50 minutes 45 seconds) Sam is knocked onto the windshield of a car. The transformer stands over him, hits the ground, then notice a bike wheel on top of the car is knocked off on to the floor. After the Decepticon says, "Where are the glasses?" The angle changes and you can clearly see the wheel back on the roof of the car again!