Continuity mistake: When Kurt and Markie are racing together in the Ice Leg, if you look closely at the part when Markie is about to crash into chunks of ice, Kurt's car has no graphics, and a lighter green windscreen.
Other mistake: Marvin survives the explosion by hiding in the refrigerator, though despite the massive blast, there is no singeing, burn marks, or even smoke around the holes that were torn into the front of the door before the explosion.