In the race between Lonnie and Gary in the funny cars the wheel rims change. At the start they are full dish wheels then at the finish of the race they have changed to five spoke star wheels.
When Lonnie Johnson catches fire, he pulls the safety and hits his fire bottles. In reality the safety is pulled before the run and is re-pinned after the run
One closeup of Meatball (seen when Lonnie gets fired from the team) has obviously been optically reversed, as evidenced by the inverted Goodyear logo on his hat.
When Lonnie Johnson blows up the Top Fueler at the end of the quarter mile you see the truck towing it and the cable that is hooked to the race car.