Other mistake: The IRA operative puts the bomb into the Audi with a timer rigged for 5:00. Three minutes and a half of time that cannot be compressed (no cuts to any other scene that happens simultaneously - and if anything, more time than that should have realistically elapsed) pass before Magnum even gets on the Ferrari and drives out of the Nest. The way it is shown in the episode, Magnum could never make the heroic save. It gets even worse at the ending; 15 seconds remain on the timer and Magnum has yet to force the Audi down the beach road, the car has to reach the end of said road, Magnum runs, on foot, to their point, convinces them that there is indeed a bomb, and they run for cover.taking cover and waiting for the thing to explode! A minute could have been spent for that task alone. (00:39:20 - 00:42:50)
Continuity mistake: When Mandy is leaning against the Audi chatting with Higgins, her towel changes position (its end pops in front of her arm, or is tucked underneath). (00:39:35)
Factual error: The villain holds Magnum at gunpoint with a weapon with a silencer. Which is useless, the gun being a revolver. (00:41:20)
Continuity mistake: Magnum jumps in the Ferrari to stop the bomb. He is wearing his blue Lacoste and beige pants. The car sprints out of the gates...and Magnum lost his pants. But it's nothing compared to the interior shot of the Ferrari that follows; he's wearing now blue jeans, and shifting gears wearing his team ring on that hand - but it was on the left hand earlier. (00:42:50)
Continuity mistake: Magnum approaches the Audi in a spot where the road is straight in longshot, but in the perspective with the camera just in front of Higgins, they are coming off a curve. (00:44:20)
Visible crew/equipment: When Rick serves special Sarduci-style sauce and wine to Magnum, set lights are reflected in Tom Selleck's shades. (00:46:10)
Continuity mistake: Rick smacks the cork on top of the wine bottle after he poured for Magnum and himself. In the next shot of the table following TC's messy arrival, the cork is almost all out. (00:46:25)
Plot hole: Towards the beginning of the episode a peculiar arrangement is presented; Magnum has to share the guest house with two stewardesses, Mandy and Suzie. The night of the party, they both go for a swim. Mandy is involved in a shooting, and following scenes include her resting at the guest house. Suzie is never heard from since. She does not have a place to sleep; it is made clear that the main house has not been arranged yet for that purpose, the Brigadier and his escort have to leave first. She is not there in the morning. She just vanishes.
Other mistake: The creepy photographer guy is taking pictures throughout the episode. His camera somehow reaches everywhere on the estate; front gates, lawn, the Brigadier's balcony, with extreme close-ups and disregard to walls and structures in the way. It's one of those magic movie cameras.
Factual error: Richard Johnson appears in the end credits as "Brigadier General Alistair Ffolkes, Royal Army", and is consistently referred to that way by Higgins and Hooker. The rank was abolished in 1921, the Royal Army would have him as as a Brigadier or a higher rank.
Continuity mistake: Rick leads Magnum to David Norman that is drinking heavily at the club. When he shouts "Nurse" at the beginning, a woman in a pink bikini holding a straw hat moves across the area to get to railing. That same woman walks in and "just reaches the railing" about 4 times during the remainder of the scene. (00:10:10)
Factual error: When Magnum looks at the collection of tapes and books from Erin, the shelves are stocked entirely with tapes marked L-250, L-500, L-750. A huge collection...for Betamax, but Erin's VHR player is a VHS, as shown by the logo in close-ups. And in fact, Magnum to watch her movie puts in close-up a T-120 tape in the machine, which is the proper format. (00:21:15)
Continuity mistake: While Magnum is at Erin's place he watches Erin's videotapes, and the TV set he uses changes style between wide shots and the TV's closeups, during the requisite scenes. (00:21:25)
Continuity mistake: While Magnum is at Erin's place, when he pops in the videotape of "acting class winter 1974" the VHS machine atop the TV is entirely silver on its top in this and a following closeup (also note there's black tape covering the machine's brand name). However, in other shots the machine is black and silver on top, which is even more noticeable in another closeup after Magnum shows David the videotape of Erin with the shotgun. (00:22:05 - 00:25:45)
Visible crew/equipment: 00.24.15 After Magnum has stayed up all night watching Erin's videotapes, Magnum is sitting in the chair holding the empty yogurt container then he stands up, and with this angle of the camera we see the normal ceiling. Soon after, twice we see set lighting at the ceiling, first, when Magnum tells that Erin didn't even blink, and second, when David tells Magnum that he loved Erin. (00:24:15)
Factual error: For the ballistic test, Higgins goes on to explain in great length that the shell contains 12 pellets, but when he displays the effect on the second target, it's blatant that there are way more than 12 holes in it - and the way the test is done, it is specified that it is the result of a single shell being fired. Incidentally, there are also more pellets than what Higgins states when he empties the shell initially -14 instead of 12 - but this last detail realistically can be assessed only if you pause. (00:29:20)