Foiled Again - S3-E7
Other mistake: The culprit does not have wounds on their hands, but whoever tampered with the box left blood inside it. If the blood is irrelevant to the case and could have been left by Higgins, then it's unclear why it has an effect on the culprit and make them admit their guilt.
Foiled Again - S3-E7
Continuity mistake: When the contestants are announced (in a thick French accent), it is said that Higgins fences from the right position. Rick later states, accusing Higgins, that "A lot of people heard Higgins ask for the right side." When the odious rival shows up, he says "You asked for the left position?" to which Higgins nods. (00:11:50 - 00:13:00)
Foiled Again - S3-E7
Other mistake: At the beginning of the episode Magnum has some banter with Higgins, but also needs his help with a tie knot he's clueless about, to the point that he can't even pronounce its name and calls it "double Winslow", with Higgins promptly correcting him. And he's completely useless at doing it. However, in the previous season's episode "The Last Page", Magnum was helping Rick with his tie and giving him expert and sensible advice about it and explicitly referencing the Windsor knot, in fact discussing the merits of the half Windsor.
Foiled Again - S3-E7
Continuity mistake: When Magnum confronts the real culprit, in the couple of POV shots they are not wearing the gloves they have in the rest of the fight. (00:43:40)
Foiled Again - S3-E7
Continuity mistake: After hearing from Magnum about Velma Troubshaw's conversation with the DA, Higgins shows up at her mansion and knocks at the door. The shadows of the foliage (and the shadow of John Hillerman himself) change noticeably at the cut. (00:37:00)
Foiled Again - S3-E7
Continuity mistake: Magnum visits Assistant District Attorney Carol Baldwin who is having her lunch break outside. She has a paper towel around the yogurt container she's eating from, but when the camera is to her left the napkin reaches the rim of the container, whenever the camera is to her right it's an inch lower. (00:21:45)
Foiled Again - S3-E7
Continuity mistake: Higgins is dressing up for the foil duel. He puts his right glove on when Velma apologizes, and when he replies that she has nothing to apologize for...he's putting the glove on again. (00:12:25)
Foiled Again - S3-E7
Continuity mistake: Before the fencing match, Higgins' old belle Velma Troubshaw approaches him and they chat. During this chat the people behind Higgins are different from shot to shot, matching only the views from the same angle. (00:12:20)
Foiled Again - S3-E7
Continuity mistake: Higgins is staring at the window after his dream. Magnum calls for him and casually walks into the study. Something changed in this second part of the scene; the black cap that will be a conversation point later is now placed across the lid and main case of the foil. In the opening view, it was entirely on the lid and wasn't on the frame. (00:03:05)