A Knight in Shining Armor - S2-E13
Revealing mistake: When Michael fights the bad guy at the end of the episode, it's easy to tell that they're both stunt doubles.
A Knight in Shining Armor - S2-E13
Visible crew/equipment: As Michael walks over to KITT and the loud mouth challenges him to a race, a light set up is reflected on the car.
A Knight in Shining Armor - S2-E13
Other mistake: After stopping Stone, Michael calls for KITT. When the car starts up, it's in gear, and the selector goes to P (park). After pinpointing the hidden entrance, the picture is of soft sand hills covering it. When KITT goes to enter, it's a defined entrance with a thin layer of stacked rocks in it.
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