Revealing mistake: Magnum neutralizes the pursuer at the gas station jacking his car. In the close-up of the wheels spinning with no traction and then stopping, the hubcap is in pristine condition, but in the next one, it sports a dent already from a previous take. (00:15:20)
Continuity mistake: Babs tells Roger "He's a private investigator" pointing at him with the same hand she had on his shoulder, and that is still there in the reverse shot. (00:31:40)
Continuity mistake: Babs finally produces a picture with Roger. In close-up, Magnum is holding it by the corner, while he had his hand at the bottom in the first shot. (00:25:20)
Continuity mistake: The morning after TC and Babs sealed the deal involving him, Magnum goes out for a swim. In the first shot, when he turns around to tell Babs that he's not doing her ridiculous knee to chest routine, the towel around his neck shows no half-squares. In the rest of the scene, the towel is folded so that there's half a square easily recognizable. (00:20:00)
Other mistake: The license plate Magnum tells Rick to check out ("55 678") is totally different from the AYX 470 the guy was actually driving. (00:16:35)
Continuity mistake: Magnum tells Barbara to go to the bathroom leaning against the windshield; his hands is turned in different directions depending on the camera angle. (00:13:30)
Continuity mistake: The scene when Barbara Terranova murders Magnum at billiards is shot with zero regards for continuity, just filming shot after shot even when the balls' positions do not match at all. Just look at the opening shot botched by Magnum; most balls are cluttering the middle of the table, but Babs takes her first shot shocking Magnum on a largely clean green rug. (00:09:30)
Continuity mistake: Magnum and Babs walk away from the phone he greatly amused Higgins with. In the background, the bar clock shows 5 o'clock, when it was 4:31 merely seconds before. (00:08:40)
Other mistake: Magnum tells Higgins he has just twenty-three hours to solve the case when both the clock at the Nest and the one at the Honolulu Lulu's Pool Hall show it's half past four. Magnum though accepted Babs' case around 11:30 AM ("11:29 at the tone", Rick jokingly said). (00:07:35)
Continuity mistake: TC tells Magnum "bet you could do it" when Magnum puts down his beer. Next shot and Magnum's hand is suddenly around the beer bottle again. (00:03:05)
Factual error: Magnum takes part to an Ironman triathlon contest, but the writers did not bother to follow the correct order of the parts of the race, which would be swim, bike, and then run. Here he cycles last.
Continuity mistake: Magnum is stretching after his morning jog in front of a bottle of Coops that turns between shots. (00:02:35)
Factual error: Magnum is scouting the prison facility with his binoculars. During the scene, the audio track to give the impression of the jungle surround has the trademark kookaburra laughter, which is not a Hawaiian bird. (00:33:55)
Continuity mistake: The titular brunette easily overtakes Magnum during his jog. The sweat patch on his shirt becomes much larger through the span of a brief cutaway, and when he joins Rick after the jog, his shirt is completely dry. (00:03:10)
Visible crew/equipment: During the fake accident, in the semi-POV shoot with the camera behind the wheel, you can spot roadside the film unit (crew and equipment) that filmed the previous shot, with the car cutting the bike's path. (00:27:00)
Continuity mistake: When Higgins starts yapping about the fascinating case of the homosexual corporals in Wales, Magnum sighs with an arm over the couch's back, changing from the earlier pose between cuts. (00:48:20)
Continuity mistake: At the end of the episode, Joy is laughing when Higgins mentions the various bands; her position on the couch changes rather obviously between shots. (00:48:00)
Audio problem: Magnum screams "SHUT UP!" to Higgins, but actually when John Hillerman is on his back during the mountain climb and mentions Lord Mountbatten, his lips are not moving. (00:38:40)
Revealing mistake: Magnum is carrying up the mountain stairway a Higgins-shaped dummy instead of the real John Hillerman, as obvious by the lifeless bounce of its legs. (00:38:20)
Continuity mistake: The bike falls down diagonal to the road lines, but it's practically parallel in the rest of the scene. (00:27:00)
