Continuity mistake: Higgins arrives at the dingy motel and walks past some broad in green. He approaches the counter, and there are bathroom doors on the left wall. The men's room has a "Out of order (Do NOT use) " sign. Said sign is hanging on the right side of the door, but just from camera angle; during his chat with the filthy porter the sign is on the left side of the door. (00:21:15)
Revealing mistake: As everyone marches towards the happy ending of the episode, the Higgins lookalike that walks by Magnum at the airport looks in fact nothing like Higgins. (00:41:50)
Two Birds of a Feather - S3-E19
Revealing mistake: The plane is supposed to be completely out of fuel and simply gliding when it passes over Magnum's head, but you can see its propeller is spinning. (00:09:15)
The Arrow That Is Not Aimed - S3-E13
Character mistake: At the end of the episode, Magnum says "You know what they say about samurai swords - you unsheathe 'em, you gotta draw blood!", but throughout the episode, Tozan drew his sword on Magnum and the villain and no blood has been drawn - in case of Magnum, there was no intention of it either.
The Arrow That Is Not Aimed - S3-E13
Continuity mistake: Magnum dives fully clothed to save Gallagher, the Tourist Shop Owner. Obviously he's soaking wet after that. Later at home, Magnum is sitting at the desk in the study wearing the same polo and jeans, bone dry. (00:35:00 - 00:36:10)
The Arrow That Is Not Aimed - S3-E13
Other mistake: Magnum mispronounces the word 'seppuku' calling it it 'seppuki', prompting Higgins to correct him. He plays the role of the usual Westerner who is unfamiliar with the word and concept. But in the previous season, in 2-9, "The Taking of Dick McWilliams", not only he already had to deal with the prospect of ritual suicide, but he spontaneously mentioned the word himself ("Seppuku? You're willing to let your daughter kill herself?") with the other person simply mentioning a vague 'honorable thing to do'.
Continuity mistake: Magnum walks back to the car after spending 4 hours at the archives. A woman with a brown dress with a red belt crosses his path and walks away. Magnum then stands in front of the parkometer (and the parking tickets), but the woman is just then passing him by. (00:23:00)
Audio problem: Magnum slips into the car in 1936 with his client out of the club. If you pay attention to the audio, there is sometimes a droning noise as if someone were using a leaf blower nearby (it's actually because in editing they cut out all sounds below a certain level - but some of it spiked enough to stay into the audible range). (00:11:20)
Factual error: At the movies, Magnum is watching a movie with Bette Davis, the first one she played in, "The Bad Sister" and comments "Keep it up, old girl, you just might have a future as an actress." Funny, but the dream is set in 1936, not 1931 when that movie came out. Implausibility of finding it in theaters aside, by 1936 young Bette Davis had already won her first Oscar. (00:30:30)
Continuity mistake: Marisa during the movie gives Thomas an appointment. When she says "That's where I hid the papers." the woman in the background is leaning against her left hand. The chat continues in the next shot but the woman's position is different and gone is the hand. (00:30:20)
Almost Home - S3-E10
Other mistake: When Magnum passes a can of nondescript soda to Bridget outside of the Navy building after the chat with Maggie, the vending machine has a big triangle of masking tape to conceal the Coca Cola logo for sponsorship reasons - however the production failed to cover the Sprite button which remains recognizable. (00:13:00)
Other mistake: The clock in the millionaire's limo has all hands (including the second hand) perfectly still. (00:02:00)
Deliberate mistake: During the episode, whenever daily newspapers are shown, they lack any indication of the date.
Did You See the Sun Rise? - S3-E1
Continuity mistake: Magnum's sling looks different before the flashback and after it when he speaks with Higgins. (00:48:50)
Factual error: Magnum gets to the airfield looking for TC the first time, at the very beginning of his drive you can see in the building in the background a modern window AC unit - that kind of device was available in 1936, but its cost certainly makes it unlikely, as it'd cost the equivalent of $8,000 today, not really something for the dingy shack it's mounted on. (00:16:55)
