Visible crew/equipment: After Rick and TC agree to the horrible terms, Higgins is "persuaded" to help them get out of jail. In the next shot at the docks, when Marsha parks in front of the trailer, multiple white tape marks are visible on the ground in front of the trailer door, then before they all leave, those white tape marks are now black tape marks and a T-mark. (00:39:50)
Visible crew/equipment: While Magnum tries to eat the hotdog, Marsha hounds him about the "rancid, decaying animal flesh with harmful chemicals and additives." When Magnum agrees to let her fix something good, Marsha starts heading up the stairs and the white T-mark is visible on the floor, where she had been standing. (00:32:50)
Character mistake: Bickering with his pretend wife after risking his neck with the falling crates, Magnums says "we can stop playing house, I can go back to being a private detective, which is exactly what I should have been in the first place." Magnum has a verbal tic during the series and he fiercely corrects everyone when they call him a private eye, or detective, as he goes only by "investigator" (the I in P.I, after all). He's using the wrong word here. (00:22:35)
Continuity mistake: When Magnum encounters his secretary and he just won't let go of her hand, in the frontal views of Tom Selleck he has his fingertips curled, while in the reverse shots the fingers are straight and don't rise above the side of her hand. (00:19:00)
Other mistake: Marsha Mackenzie is supposed to be competent with certain aspects of men care; she comes from a wealthy family and she has been taking care of the men in her family all her life. And Magnum does show up at the Kamehameha club with a nicely done knot on his tie. When we actually see the actress tie that same not metaphorical knot though, it's very clumsy, crooked and differs in between shots (it's also done on an unbuttoned shirt).
Continuity mistake: Harry MacKenzie gets two big splotches of cake on his suit. Dances with his niece, and then comes back to the buffet table taunting his nephew. No (or at least, very little) splotches at first, but in the closer view his suit is all soiled again. (00:06:20)
Continuity mistake: Rick and TC are at the wedding buffet. Behind them as they toast in memoriam of Magnum there is a dancing couple. She has a pink hat and her date has a yellow jacket. There's also a black guy in a brown jacket busting some groovy moves of dad dance. Both are also behind Higgins as he arrives, though. The couple also walks back and forth padding the background in the rest of the scene. (00:03:50)
