Other mistake: As KITT has the guy pinned by the fence, asking questions, the passenger mirror is angled out in an impossible angle so there is no reflection.
Continuity mistake: When Michael is evading the earth movers you can clearly see his left hand at the 12 o'clock position on a normal round steering wheel, rather than the aircraft-like yoke. (00:12:38)
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