Other mistake: The episode opens with the Coast Guard finding the boat owned by Marion's father empty. It's a small sailboat. Later Magnum visits it with Marion, and the boat is a small double decker yacht that looks entirely different. (00:01:50 - 00:09:30)
Continuity mistake: Marion and Magnum walk to the taxi for the goodbye. He opens the door, and her hair is all behind her back. Switching to the frontal view, she has her ponytail in front of the left shoulder. (00:46:00)
Continuity mistake: To nobody's surprise, Magnum emerges from the ocean unscathed. Between shots, his hand and Rick and the villain's change positions. (00:45:15)
Continuity mistake: After the culprit and Marion are aboard safely, there's a shot of Magnum with the bomb in close-up, followed by another one where the timer went back almost at the starting point. (00:44:40)
Continuity mistake: Magnum puffs holding Keone's photo with his right hand - which was both hands before the sudden cut. He then drops the photo on the table, but when he digs the map from underneath the pad, the photo changes position entirely again during a sudden cut. (00:29:30)
Plot hole: Magnum asks Mac to "put together a list of ships that went down in that channel in the last 200 years." He gets the list, and it turns out of the ship of interest, amongst the many, is the Eldora, "a Spanish galleon used to carry the plunder back from Spain's numerous conquests." That sounds like something quite more ancient than 200 years, however it can be said that galleons were still in use in the early XVIII century. However, when Professor Martinez hears the news, she says that it supports her theory of early contacts between native Hawaiians and Conquistadores, which would put it centuries off range again. It also begs the question; why would the US Navy intelligence know of that galleon (but without any location or additional info) but the scholar at the university who is studying and publishing a book on that very subject is totally oblivious about it? Even Higgins heard about it.
Continuity mistake: Higgins wants to show Magnum the rare Kudu buck in a book. Picking it up from the shelf, causes 3 other books to lean forward. In the close-up that follows, just one book is misplaced. (00:26:30)
Continuity mistake: When Marion asks "He's dead, isn't he?" hair pops in front of her shoulder suddenly after the cut. In fact, throughout the whole scene notice how in close-ups it's in front of her shoulder, in wider ones behind her back. (00:24:25)
Revealing mistake: In the wider shot, the dead body the police covers has much more of a receding hairline than in the close-up. (00:23:55)
Continuity mistake: Magnum is saved, and it's time for the others to concern themselves with the assailant. Rick dives in a close-up to look for him. The mask is really close to him all of a sudden, and in a different position (practically touching Magnum's chest) in next shot. (00:23:20)
Revealing mistake: When the masked Hawaiian hits Magnum in the back with the club, for a second you can see distinctly Tom Lupo (stunt double) 's face instead of Tom Selleck's. (00:22:25)
Continuity mistake: On his way to Rick's boat, Magnum stops to talk with the witch lady. A very short drive and he's then in front of the boat. Rick is in the background and he starts moving and preparing to greet him, but in the close-up it's as if he has been chilling all along and only then decides to be active. (00:21:20)
Continuity mistake: Marion Hammond unlocks the boat door and finds a mess. Between the establishing shot of the interior and the one with Tom Selleck inside, the towel on the ladder moved, and a diary tossed on top of the typewriter flipped without anyone coming anywhere near. (00:10:05)
Visible crew/equipment: When Magnum tips his hat to the group of Hawaiians who don't want any Haole messing with their channel, in his sunglasses there's the reflection of a set light and the crew. (00:08:40)
