Continuity mistake: When Michael and K.I.T.T. go to rescue LT. Ladd off the firing range,the steering wheel isn't K.I.T.T.s usual steering wheel, it has metal bars coming out to the handgrips.
Character mistake: The sign in front of the tank Lt. Ladd is trapped in reads "ORDINANCE TESTING FIELD, DANGER.", but an ordinance is a type of decree or law. They probably meant 'ordnance', which is another word for artillery.
Continuity mistake: When Michael starts to scrape the blue paint off the shell, he scratches across the blue band and you see a few scrape marks where the paint is gone and it's white, like the shell, underneath. In the close up, it's slowly scraping such a small potion of the paint off and you see it's yellow underneath now.
Continuity mistake: When Michael notices the accident report folder, the folder is touching the red candy basket. When goes to steal it by putting it under the basket, the folder is now further away.
Visible crew/equipment: As Michael and Robin go to get into KITT on the firing range, the filming crew and equipment are reflected on the light cover on the back end of the car.
Answer: I would say that unless there's visual evidence it was another K.I.T.T. car, as in you could see the bar scanner or cut steering wheel, people on here would correct the mistake by saying more than one 1982 Pontiac Firebird Trans-Am was sold and there's no reason it's meant to be a random car.
Bishop73