Character mistake: The party is supposed to be "One of the premiere social events of the season", but the only people invited (Higgins knows for sure who is gonna come, so it's not like there's low attendance because of the weather) are a Prince from a fictional European state nobody knows about with his commoner wife, the editor of a poetry magazine that needs Robin's funds to survive, a sports star and Robin's accountant. 5 people in total, already all in Robin's pocket, and nobody else in attendance. While you could say that having royalty and a golden glove winner is certainly noteworthy, those people don't meet anyone else. Hardly a 'social event'. (00:04:00)
The Case of the Red-Faced Thespian - S4-E12
Character mistake: Magnum quotes in his mind (right after the $20,000 turns up in Higgins' room) and then out loud (during the denouement) that "Old wounds heal slowly." The quote is from a movie he watched earlier...but it said "DEEP wounds heal better slowly." (00:30:55 - 00:35:40)
Character mistake: The coach of the Jororo team makes a joke about being cut by the king "Like Robespierre did to Louis XV in '89." That would have been Louis XVI (and not in "89" but (17) 93, although the year of the French Revolution is correct). (00:25:10)
Character mistake: Higgins remembers having met the sisters "37 years ago this July", and shows a "theatre program from Blackpool the summer I completed my upper second at Sandhurst." Considering the episode is set in 1983, Higgins would have still been in military academy in WW2, which contradicts the plethora of experiences in North Africa and Burma. It's more likely that John Hillerman misspoke and it was meant to be "47 years ago", before the war. (00:37:30)
Character mistake: Magnum is holding a stinky pickled egg while he bickers with his friends in Rick's car. TC calls the store chain Magnum has been hired to protect "Day-N-Night" instead of "Day-N-Dark." (00:22:00)
Character mistake: Magnum mutters that they can still make it to the second half of Bambi, "Thumper is probably still alive." Thumper does not die in "Bambi", as Magnum should know since he's seen the movie already. Props to him for being cautious with spoilers casually leaking a fake one, then?
Character mistake: Waldo's database entry from the CIA archive is quite odd. The most striking part is the "Basketball scholarship, 1983." Despite the way Rick reads it and reacts to it, the only way it could make sense if it referred to Waldo's son, or he'd have gotten it at the ripe age of 42 and 20 years after graduating from Yale. But it makes no sense that it would be there on his file, and contrasts with the succinct file on Skuler. (00:25:00)
Character mistake: Rick says "It's working, here it comes" a second too early, when the kid hasn't finished typing the name and hasn't launched the search just yet. (00:24:40)
Luther Gillis: File #521 - S4-E2
Character mistake: In the opening shot of the "Busy B", the name of the show on the marquee is "To young to care" (00:30:40)
Luther Gillis: File #521 - S4-E2
Character mistake: Agatha says that Higgins is teaching them "kung fu" although they all wear a karate gi and belts. Higgins then asks Luther to be a stand-in for the "jumping kick" demonstration, but the old lady charges at him with her hand at the ready for a karate chop. (00:16:00)
Character mistake: Higgins' anecdote inflicted on Rick says that In Kwangju. In '49, Corky Boswick got kicked in the head during "Sunday of the Queen's birthday party", but at the time, George VI was still King, and would be until February of 1952. (00:42:25)
Character mistake: Rick reveals Magnum that a certain person committed "security fraud." That'd be securitIES fraud. (00:40:20)
The Taking of Dick McWilliams - S2-E9
Character mistake: Rick describes to his buddies the kidnapper's car as "a yellow Bronco." It's a jeep and it's orange/brown with a white roof. The description is so off that it's a miracle they found it to begin with. (00:16:10)
Wave Goodbye - S2-E7
Character mistake: At the station after the release of the first suspect, Kelly does the good cop routine and apologizes for his Sergeant, saying he does not like a private eye telling him how to do his job. Magnum 99% of the time during the show corrects people saying "private eye" with "private investigator", but here, he does not. (00:16:20)
Wave Goodbye - S2-E7
Character mistake: At the end of the episode, the cop reads the culprit his right, twists his arm and exits stage left with him. But 'left' happens to be towards the ocean, away from the patrol car. He also leaves the gun behind, lying in the sand. Worst cop ever. (00:47:45)
Character mistake: Sitting at the club's beach bar, when TC urges him to give him the rest of the money Rick says "eighty" when he is in fact giving at least the 9th 10 dollars bill. (00:16:20)
Character mistake: When Magnum looks at the pictures Higgins gave him, he sees one with a flare that will require him to ask Higgins to do some movie photography magic to remove it. However next to it there's a picture with just a slight less zoom that has no such flare. Magnum for no reason entirely ignores it while he only needed to grab a magnifying glass instead of begging Higgins and wait for the film to be developed again. (00:29:30)
Character mistake: Higgins holds his glass of brandy with Magnum's photos in the other hand and says "I don't know if you're pulling my leg, as you Yanks put it." It's really not an exclusively or typically US expression; in fact it originated in England. (00:27:35)
Character mistake: Magnum and Billy Joe Bob face one of Ito's goons. The guy is supposed to be competent with nunchakus, but he simply waves it around with no skill and in the close-up of his warrior yell, he strikes a pose with it but you can see at the bottom of the frame he misses the catch and does not grab the other stick. Obviously the extra was hired simply because of the looks and ethnicity but had never used this goon's supposed weapon of choice before. (00:24:55)
Character mistake: The day of the race, Higgins reacts to Adelaide mentioning Norman as if it were the first time he ever heard the name, but he was present when she mentioned him, and the case. Not being all that involved, technically he didn't have to remember that, but he remembered the detail of the uncle, and forgetting that the woman was talking about someone being murdered, is quite odd - and is just done for the cheap gag that follows.