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: During the very last race, Lightning McQueen gets next to the green car, and the reflection of that green car's chrome "C" emblem is seen on Lightning McQueen's hood. However, the C is facing the right way. Since the C is placed on the green car in the correct direction, the reflection on Lighting McQueen should be a mirror image.
Other mistake: Lightning Mcqueen is trying to become the first rookie in Piston Cup history to win the Piston Cup, but Doc Hudson won the Piston Cup in 1951 the first year that Hudson Hornets were produced, which also would have made him a rookie.
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.
Other mistake: At the start of the film when the commentators are explaining the tie situation between the 3 cars the green arrow to the car is out of alignment and misses the car, instead pointing at the track.