Right after Jackie Chan/Richard Kiel's car is dropped out of the plane, they're chased by cops. To make them invisible, the car hovers above the ground. As the car is lowering, you can see the shadow of the crane on the ground, lowering it down.
At the roadside fruit stand, Arnold's racing outfit has
a few watermelon stains on it even before Jackie breaks the melon, but his outfit is perfectly clean when he drags Jackie away at the end of the scene.
When the CHP Sergeant is chasing the military car driven by Captain Chaos, the nuns, and JJ McClure, the police car's top emergency lights change from yellow and red in up close shots, to red and blue in long shots. Also, the lights are switched on and strobing when seen in long shots, but not on in up close shots.
When Blake and Fenderbaum try to run the military car off
the road, the overhead shot of the accident shows them being cut off by a red/gray Dodge Daytona, not the solid red Corvette they were driving.
Before the big fight scene near the end there is a scene on a long straight road showing all the cannon ballers coming to help. In this group of vehicles lead by the pickup truck is the yellow sports car that broke down on the two Lamborghini girls early on in the race.
During Hal Needham's scene at the beginning of the race, he doesn't have the punch card. After the Big Foot truck rolls up and over his car, he has the punch card that he flicks over the damaged car's windshield.
When JJ an Victor are stopped by the Sheriff, on the Sheriffs hat the badge reads Deputy Sheriff. If he was the actual Sheriff it would read as such. If he was a Deputy h would have to correct them by stating he was a Deputy.
Near the end of the movie when terry and the limo are pulled over by the cops, you can clearly see a big hill behind the car on the left side, however all the in car shots show a clear view behind the vehicle through the back window showing those shots were not recorded in the same place.