Visible crew/equipment: By the car exit of the Mokihana, both in coach Lum's car and in the Ferrari you can see the reflection of people standing by to film the scene. (00:44:10)
Sammo
Other mistake: With power out Magnum somehow lights the gas stove with the knob, which is electric. Should have used a match. (00:26:40)
Don't Eat the Snow in Hawaii - S1-E1
Continuity mistake: When Magnum drops the ring out of the envelope, nothing is near it as it's shaking. In the close up shot, it's next to keys. (00:44:20)
Bishop73Revealing mistake: One of the party guests opens the door of the fridge and you can see behind the set instead of looking into the fridge. (00:32:40)
Continuity mistake: The opening of the show starts with Magnum driving off with the iconic Ferrari; however it has a license plate number, 56E-478, which is not the one seen in 99% of the show. It comes from the pilot episode, where the vanity plate ROBIN-1 had yet to be introduced.
Sammo On the Fly - S7-E15
Visible crew/equipment: When Magnum successfully lands the plane he starts shouting about the brakes, then in the following shot of "Mac" lying in the hospital bed, the black T-mark is visible on the floor, in front of Higgins. (00:44:25)
Super Grover On the Fly - S7-E15
Visible crew/equipment: While Higgins is standing beside TC's hospital bed there's a boom pole and mic hovering low in the area of Higgins' legs, and it can be seen in the two wide shots from behind Higgins, especially when Rick mentions the noontime news. (00:06:40)
Super Grover On the Fly - S7-E15
Visible crew/equipment: After Magnum realises TC has been shot, in the following wide shot with TC in the hospital bed, two black T-marks are visible on the floor, where Magnum stands, then a third T-mark is visible on the floor closer to the TV. (00:05:40)
Super Grover Visible crew/equipment: Inside Benny's glasses when he is taken back to the Estate is the reflection of the set light screen. (00:39:10)
Sammo Continuity mistake: Rick tells (and shows!) Magnum that he's writing "a recipe for Veal Marsala for my mother back in Chicago." But the key plot element of 4-4 "Distant Relative" was that Rick raised his sister by himself, because Chicago was "a tough town to grow up in without any parents."
Sammo 
Continuity mistake: For the first episodes (minus the plot), the opening of the series features the Ferrari with two different license plates. The opening shot shows the ROBIN-1 vanity plate that is in every episode but not in the most well known version of the opening (with the iconic Mike Post theme music used in all the other seasons), and the following shows the license plate from the pilot.
Sammo Other mistake: Twice in the episode it is explicitly said that Magnum's phone has been disconnected, and that Higgins checked with the phone company. Yet at the end, it turns out 'the lads' chewed on the cable. Surely the phone company wouldn't tell the estate manager that the line has been disconnected for billing problems (so, a well determined administrative issue with proper paperwork done) when it's a wiring problem.
Sammo Continuity mistake: Magnum and TC are talking at the beginning of the episode, by Rick and his peachy polo. Magnum has always his hands on his hips in TC's close-ups and in front of his belly in the wider angle shots. (00:02:15)
Sammo Other mistake: Finally the gang is set free; the policeman says "Your bail arrived." Magnum asks "Carol Douglas?" But Carol's last name is Baldwin in the other episodes she's involved in. (00:35:30)
Sammo Continuity mistake: Magnum and TC hi-5 at the beginning of the episode. The football bounces at distance from TC in the first shot, but it's right at his feet after their hands clapped. (00:02:00)
Sammo Continuity mistake: Magnum is bullied into going with Carol's lame plan. The very first shot of him and TC on the Ferrari on their way to block the drug lord shows TC wearing a white sweatband on his head he does not have in the rest of the episode; it's recycled from 1-13, All Roads Lead to Floyd, and you can even spot the car typical of that episode. (00:29:10)
Sammo Continuity mistake: Magnum begins to open the safe; the sensor with the red wire is in left position, black wire in right position. When he removes the sensors, it's the other way around. (00:23:00)
Sammo Continuity mistake: Drunk Carol is telling Magnum why she was fired. As she says "They took it away from me", her hand is in front of Magnum's, and yet it is on top of it at the cut. (00:06:00)
Sammo Revealing mistake: TC runs into Higgins avoiding him in the front view with John Hillerman, and hitting him when he's replaced by a stuntman. He also is sprawled face down on the lawn with one or both arms up. (00:02:45)
Sammo 
