Other mistake: After the first race, in the scene where Lightning is rushing out on the stage thinking he is the winner, loads of confetti is shot out when the King and Chick Hicks gets onto the stage. The confetti is then falling down, but not a single flake hits any of the cars. However, in the following shots, you can see plenty of it on the stage underneath the cars, even though they haven't moved.
Other mistake: When Mack wants to pull over because he is getting sleepy a car drives by with a mattress on the roof. There is no reason to have a mattress in a world without people, the cars sleep right on the ground/floor.