Continuity mistake: When the two Lamborghini ladies are stopped by the police the first time, you first see the lady in the red dress from the front. Her zip is obviously up. In the next shot you see the other race participants raging by. The lady is shown from behind now. When you see her from the front again, the zip is down. Now we can see her from behind, and as we see her from the front again the zip is up again. Then she puts it down again to show the sheriff her driver's licence.
Continuity mistake: We can see Sammy Davis Jr. as he slits Burt Reynold's car´s tires. Later we can hear Reynolds as he says that they lost more than 2 hours by fixing the damage. But how comes that at the petrol station, Reynold´s car leaves even before Sammy Davis Jr. and Dean Martin arrive there?
Deliberate mistake: In the last sprint towards the finish line, before they have to race on foot, the Lamborghini passes Fenderbaum and Blake. The red Ferrari they are supposed to be driving, is on the bed of a truck being towed. Notice the height difference between the two cars; about ten seconds later the two cars are pretty similar in height.
Continuity mistake: JJ and Victor's ambulance's engine sounds are dubbed, and a few times you can hear the sound of shifting a manual transmission when the ambulance is shown to have an automatic.
Factual error: Looking at the dimensions of the low-loader and the dimensions of the ambulance, Victor is laying at 90 degrees to the ambulance as we see a shot from the front of the vehicle (over the lower wishbone). There's no way that he could mend the transmission without his legs sticking out the tarpaulin and not being seen.
Continuity mistake: In the scene where the GMC pick-up truck jumps the train, you see the front of the truck being damaged during landing. Later in the movie, the truck is undamaged.
Continuity mistake: After the girls in the Lamborghini are pulled over, they get passed by several other Cannonballers. Blake's Ferrari passes them twice.
Audio problem: When Mel Tillis and Terry Bradshaw are trying to "re-tune" their race car, when Bradshaw tells Tillis to "hit it one more time", the car makes the distinct starting sound of an older Chrysler when the car was a Chevrolet. Also, how does Tillis starts the car? He has one hand on the steering wheel and his other hand is on the doorframe.
Revealing mistake: Several times in the fight scene near the end, it is painfully obvious that punches are thrown by the characters and are heard connecting but never actually touch anyone.