Revealing mistake: Just after the Buick spins around to knock the trailer loose, we see the Buick speeding away backwards alongside the truck. If you look carefully you can see the REAR tires are steering, not the fronts. This car was modified with the body mounted backwards on the chassis because the transmission only has one reverse gear, so to get the speed and handling needed, the car had to be going 'forward' with a 'backward' body.
Revealing mistake: When Dom and Letty get out the car at the crash scene, there is a light reflected in the paintwork quite low. When the camera pans out you can see it's not the moon due to its position, and there is no other light source around that could cause the light to be reflected so low on the car.