Luther Gillis: File #521 - S4-E2
Other mistake: Luther decks one of the old ladies with a punch. When he strolls past them after slipping Magnum a mickey, he looks back at them, and one in particular, who is sporting a patch. It is not the same lady he punched earlier. (00:17:35 - 00:21:30)
Luther Gillis: File #521 - S4-E2
Other mistake: The guesthouse scene with Magnum and Luther opens with a prolonged gag about Magnum "finally" getting an answering machine. It is said that it's the first time he gets one. But in the season 1 finale, "Beauty Knows No Pain", Magnum's client Barbara Terranova commented that the message on Magnum's answering machine mentioned the club. (00:03:25 - 00:18:00)
Luther Gillis: File #521 - S4-E2
Other mistake: For the first 2/3 of the episode (up until their second prison visit) Magnum is wearing the same watch he had been wearing for the previous three seasons, with a leather strap. For the last part of the episode he wears the pepsi bezel watch with a metal bracelet that he inherited from his father and was the focus of the previous episode and will be his regular watch for the rest of the show, in kind of a retcon.
Luther Gillis: File #521 - S4-E2
Other mistake: Higgins is on the lawn doing his martial arts demonstration, so there's nobody to open the gate that Luther passes in reverse gear. (00:21:55)
Luther Gillis: File #521 - S4-E2
Other mistake: The policeman opens the closet door in the most transparent "a corpse is going to fall off from here and I know it" way, stepping away from it and even looking down where the body will drop. (00:05:45)