When Devon shows Michael the black cassette tape, you can clearly see that both sides of it have a label with a white stripe. But when Michael puts the tape into K.I.T.T.'s in-dash player, there is no label - just a blank black cassette housing. Then when Michael ejects the tape after listening to it, the white-striped label is on it again.
Due to his "mudbath" and other environment-related traumas during his trek through the swamps, K.I.T.T.'s grille-mounted scanner is partially disabled - several of the red lights are not working throughout much of the movie. Yet in the final fight scene between Michael and the bad guy, all of the scanner's lights are working again. Then shortly afterwards, in the scenes of K.I.T.T. surrounded by the dogs and the lady saying goodbye to Michael, the scanner lights are again not all flashing.