Continuity mistake: At the hospital, there's a push button desk phone on the table between Lee's and Magnum's beds. There are two closeups of this telephone when both Lee and Magnum lift the handset, and the entire telephone changes to a multi-line desk phone. Plus, in Lee's handset closeup, his hospital ID bracelet changes from narrow to twice the width, and in Magnum's handset closeup, the large floral box of tissues change to a short box of tissues. (00:24:10 - 00:27:10)
Luther Gillis: File #521 - S4-E2
Continuity mistake: At the start, when Luther gets out of his car the license plate number is AUF-365, but after Magnum's visit to the ER, when Luther is at Robin's Nest his plate number is AUF-366. It's the same rented Ford Fairmont Futura. (00:02:40)
Luther Gillis: File #521 - S4-E2
Visible crew/equipment: After Tanaka gives Magnum one day to come up with answers, it cuts to Magnum and Luther in the Ferrari. In the shots facing Magnum, visible on his sunglasses are the reflections of filming equipment equipment directly in front of the windshield, as well as attached to the driver's side door. The device on the door is a bit visible again twice, after they're released from jail the second time, and after Luther's visit to the ER. (00:28:55)
Luther Gillis: File #521 - S4-E2
Continuity mistake: When Luther and Magnum are arrested at Keanu's cockfight location, Luther is wearing his red Hawaiian shirt with palm trees design, then when Tanaka calls them both "walking menaces," the design on Luther's shirt is different now, though it's still the same style. (00:25:50)
Visible crew/equipment: During the flashback, while Magnum is on the longboard paddling five miles to the island, the chopper is flying over the open ocean when TC starts talking to himself about Magnum bucking for a section-8, and as the chopper's nose moves upward the reflection of set lighting, etc, can be seen on the windshield. (00:17:05)
The Case of the Red-Faced Thespian - S4-E12
Revealing mistake: When Magnum and friends are trying to figure out of the invitations mystery, the telephones on Higgins' desk are unplugged. (00:36:00)
The Case of the Red-Faced Thespian - S4-E12
Other mistake: In the opening credits, the title of the episode appears without hyphen. (00:01:35)
Continuity mistake: Serious matters of Little League espionage are discussed as TC accuses Magnum. When he says "They beat Taiwan" he has not a hand on the cooler full of Gatorade with badly camouflaged labels, but he does then, right at the cut. (00:05:40)
Revealing mistake: When Danny runs away from the baseball field, the camera pans towards the left and stops while several people in the fictional Jororo army uniform storm the area on foot and jeep. But to the far left in the distance, you can spot a legit Hawaiian cop at the roadblock used to film freely in the street. (00:02:35)
Revealing mistake: Danny runs away from the game, and is chased by army people on a jeep. The two cars (the jeep and another one parked there) have fictional license plates, supposedly from Jororo, since the opening caption specified "The Jororo Islands." However when the secret service guy and the coach have caught up with him, two cars in the supposed back alley of a normal Jororo suburb have Hawaii license plates - where the series was filmed. (00:03:10)
Revealing mistake: The prince runs away from the game and into the market, where army people on jeeps chase him. They crash goods, topple carts and all sort of destruction, but the extras in the market are actually having a great time and most of them just laugh while people with automatic weapons shove them aside and spill on the ground their stuff. (00:02:45)
Operation: Silent Night - S4-E10
Revealing mistake: When Magnum and friends sing "Silent Night" at the end, fake starry night background and dry ice clouds are perfectly discernable. (00:46:00)
Operation: Silent Night - S4-E10
Other mistake: The three friends mistake Higgins' footprints in the sand for a pirate's. They find him and they have their explanation; Higgins is carrying a cane and some palm leaves; dragging the palm leaves, he involuntarily erases the prints of his foot, while the cane leaves a circular print akin a wooden leg's. That makes no sense, because as it is shown, Higgins is holding the cane in his right hand, and dragging the palms with his left; he'd wipe the prints of his left foot, if anything. And yet when Rick pointed at the prints, it was obviously a left footprint. (00:18:20)

Operation: Silent Night - S4-E10
Continuity mistake: TC is working by the tail rotor to fix the vibration. It's red with thin white stripes. By the end of the episode the rotor is the opposite; white with red stripes. (00:06:40 - 00:44:20)
Operation: Silent Night - S4-E10
Audio problem: On the beach, TC is comforting Higgins who is depressed for the unceremonious ending of his sailing adventure. He tells him "It could have worked." There's a cut to Higgins and silence between the two, but you can spot at the edge of the frame that Roger E. Mosley's mouth is moving with no sound. (00:38:20)
Operation: Silent Night - S4-E10
Continuity mistake: Magnum and the others push Higgins' makeshift boat into the sea. Water does not even reach Magnum's knees, but as Higgins keeps pontificating from the sinking vessel, Magnum is thigh deep in salt water, with splashes all over the crotch. (00:34:00)
Operation: Silent Night - S4-E10
Continuity mistake: By the Japanese wreckage, Higgins calls it a "reconnaissance plane." Rick has his arms folded. Next shot and he has his arms down; takes him a couple seconds before he folds them. (00:21:05)
Operation: Silent Night - S4-E10
Continuity mistake: When the three buddies rush into the clearing before Higgins and he calls them "cannibals", he holds the palm branches at hip-height in the shot from behind, breast-high in the front views. (00:19:10)
Operation: Silent Night - S4-E10
Continuity mistake: Rick first follows Magnum carrying branches. When Magnum passes him an additional one, look at his shirt; from the side you can see it's almost entirely unbuttoned. In the front view he has "just" the top three undone, and then he takes off his shirt when Magnum spooks him. (00:13:30)
Operation: Silent Night - S4-E10
Continuity mistake: In the opening shots, the helicopter is the N58243 one with flotation pads, but as soon as it starts malfunctioning, the pads thin up and we switch to the usual chopper. The skids change shape back and forth again once. (00:02:05)