Continuity mistake: Judge Robert Caine comes out of the hotel while Magnum is munching Higgins' lunch and reading the articles. A couple (she wears purple) walk by him. Magnum spots him and scarfs down the last bit of the sandwich, closes the bag, starts the car; a good 30 seconds passed before he's out of of the parking lot, and yet next time the camera goes back to the judge, the couple from earlier is still passing him by. (00:21:40)
Revealing mistake: The article Magnum reads in his Ferrari, by the title "Local judge offered high court seat" begins like this; "A former Los Angeles Veterans young actress, a bone of contention feet wide and eight feet high. Powered by electricity, it carries its own won't even pay that." Filler text can't get better than that. (00:21:25)
Visible crew/equipment: Magnum asks the judge what could that woman from 40 years ago have on him, and as he waits his answer, he looks down. His sunglasses then are tilted in a way that reflects the lights of the set. (00:08:50)
Continuity mistake: Magnum walks up to his client, waiting on the beach in a suit. He tells him he's flattered; José Ferrer's arms are folded, at the cut they are down his side and only then he folds them. A very similar flub happens seconds later; he pulls the letter out of his pocket, and does it again in reverse shot. (00:07:05)
Continuity mistake: In the intro, Bobby holds Diane telling her nothing will go wrong - last famous words. Between the first shot and the close-up, her hair changes position on the shoulders, and when she hugs him, her hand is off and on his shoulder at the cut. (00:03:55)
Continuity mistake: When Magnum shows Rick the picture, Rick untangles his fingers twice in the separate shots. (00:11:30)
Continuity mistake: Rick puts the $50 note horizontally for his bet; when Magnum cashes it in, it's vertical. (00:29:20)