When Michael finds out that K.I.T.T. has been completely dismantled, there are boxes which hold most of his parts. You can see a normal car steering wheel sticking out on the top box. K.I.T.T. never had a steering wheel; he had a steering yoke.
Michael has fitted KITT's microprocessor unit in his 1950s Chevy. When the camera pans from Michael in the driver's seat to the scanner in the grille, a crew member can be seen reflected in the chrome.
Most (if not all) the police cars in the movie are Chevrolet Berettas. In the scene where the police are chasing the decoy van that is believed to be hauling the guns, the police cars are clearly Chevrolet Berettas. However, when the villains open the back of the decoy van and fire a missile at the lead police car, the target police car suddenly changes to a totally different car upon impact of the missile. This can be clearly seen with the differences in wheels and headlights in the clips following the explosion (the car on fire has two headlight sections, whereas the Beretta has one).