A Thousand Pardons -- You're Dead! - S2-E1
Factual error: Danno, who's posing as a Marine, has hair that's far too long to be permitted in the Corps. In fact, all of the Marines in this episode have non-regulation (too long) haircuts. 'T'was the same then as it is now: US Marines are given "buzz jobs," and hair longer than an inch is not allowed.
Factual error: 19 1/2 minutes in. They pull over a car and run the plate. Malloy tells the driver the car is registered to a Volkswagen. He should have said the plate is registered.