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.
Character mistake: When K.I.T.T. is talking about rubies he refers to them as a crystalline form of carbon. Ruby is actually crystalline aluminium oxide.
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