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)
Visible crew/equipment: Magnum and his reluctant passenger arrive to the designated location for the hostage exchange. As the van stops and the camera pans to the left, the camera casts a large shadow on the car of the bad guy. (00:40:40)
Audio problem: In the highlight reel that comes before the opening, Mac's computer does a scrambled electronic sound different than the cleaner bleeping sound used in the actual episode. (00:00:05 - 00:11:50)
Revealing mistake: Right after Newton drags his girlfriend to the ground and before Magnum spots him and takes aim, Eric walks at the top of the barge...but it's not the Eric we see then in close-up; it's a burlier guy dressed the same.
Continuity mistake: For the final confrontation with the rogue Delta agent, Magnum moves from the van where he (foolishly) left unguarded the bad guy with the damsel taking cover behind one cable drum, to another. He looks back in a close-up as he clings to the drum, and the van is far in the distance behind another drum. He then looks forward, towards the tower where the agent Tobin is hiding, and decides to move. Only, we see that his sortie is beginning from the large spool the van is parked next to. (00:42:50)
Continuity mistake: When Agent John W. Newton is shot to the shoulder, he drops his M-16 behind him, a couple meters above his head. Magnum retrieves it from the vicinity of his foot. (00:46:00)
Continuity mistake: Magnum runs away from Tobin's fire, ducking by a large piece of construction equipment. In the closer shot that follows, that element casts a large shadow Magnum repairs in, and that was nowhere to be seen earlier. (00:43:20)
Audio problem: Magnum found Eric at the abandoned building. In their unlikely chase, at one point Magnum gets by a railing he ducks underneath to get - questionable - protection. If you look at the left of the frame, you can see the puff of smoke and debris that would imply a bullet being fired, but there's no audio for that. (00:28:50)
Continuity mistake: Higgins and the other higher-ups at the King Kamehameha Club march towards Magnum after the shooting incident. Their positions change between shots - Rick's thumbs move from the belt to his front pockets and the guy with the powder blue jacket is behind the guy with the mustard one. (00:26:05)
Continuity mistake: When Magnum stands up telling Newton he wouldn't give him the directions to Diamond Head, Rick in the background is leaning against his right hand in the first shot and has both hands on the file in the second. (00:22:55)
Continuity mistake: After telling Agent John W. Newton to "go suck an egg", Magnum walks away...but no so far, because he is leaning against the railing just across. His right hand is far away from the vertical beam in the first wide angle, and on top of it in the next closer view. (00:23:00)
Visible crew/equipment: When Magnum bargains with TC the tune-up cost ("I tell you what I'll do"), you can spot the camera crew in Tom Selleck's shades. (00:19:40)
Continuity mistake: Magnum explains that the "delta section" of the US Army does missions involving stuff like sabotage, assassination, terrorism (!). Laura protests saying "Eric couldn't have been a part of anything like that." She says it with hair in front of her right shoulder, in contrast with the previous shot. It switches back and forth again with the change of angle. (00:12:10)
Other mistake: After hitting the "Delta block", Magnum tells Laura about it. The footage that opens the scene is taken from a previous episode, 1-3 "China Doll", around 00:35:00: same girl in orange bikini showering on the beach, same couple walking by the surf (he has kaki shorts and a blue hat, she is wearing orange). (00:12:00)
Revealing mistake: In a fun bit of 'movie computer science in the 1980s' that ends up with a beeping alarm and odd full-screen warning in ugly vectors for protected data, Mac types the name of the Lt. Eric Tobin with keystrokes that can't possibly match those letters. (00:11:15)
Continuity mistake: Laura tells the story of the 'visions' she has of Eric Tobin. More and more engrossed, she says he keeps "falling and falling." Her long mane is off the left shoulder. Cut to Magnum for a second, and she's got hair everywhere around her face, only to have again face and shoulder clear of hair in the next change of angle. (00:09:10)