Factual error: After the opening credits it cuts to Klinger at Mail Call, and Father Mulcahy's reading Ring Magazine which is dated December 1969, 16 years after the Korean War ended.
Visible crew/equipment: While BJ's holding Peg's letter and telling Hawkeye about being homesick and depressed, the edge of the Swamp set can be seen at the top, left corner of the screen.
Visible crew/equipment: While in the mess tent, after Margaret's grossed out by the smell and walks away we hear Charles start playing again, and when Colonel Potter says, "Just make sure the three of you work this out fast," in this shot we can see the actor's T-mark on the floor between Potter and Hawkeye, where Margaret stood a moment ago.
The Trial of Henry Blake - S2-E8
Visible crew/equipment: After Henry's cleared of all charges, when Margaret drops the crumpled paper and storms out of the room with Frank, we can see chalk marks and a T-mark on the floor where Frank was standing.
L.I.P. (Local Indigenous Personnel) - S2-E7
Continuity mistake: When Lieutenant Willis wakes up in the Swamp and puts his shirt on he's wearing his dog tags, but when he tosses the papers and puts on the rest of his clothes the dog tags have suddenly vanished, then they reappear, vanish, and reappear again.
Visible crew/equipment: When Klinger walks into Henry's office while Margaret and Frank are there, we can see the chalk T-mark on the floor behind Margaret where Radar was standing moments ago.
Other mistake: During this episode, Trapper and Hawkeye keep switching Frank's pistol with other things. When Frank's training his South Korean platoon, Trapper, Hawkeye, and Radar show up all decked out, and while Hawkeye's telling Frank that using the anti-aircraft gun on the compound will draw enemy planes, etc., there's a pistol in Frank's holster. When Frank turns around, we see that Trapper's right arm is bent over his fly swatter the entire time until he steps away from Frank, and when Frank draws from the holster what he believes is the pistol, he pulls out a plunger, and although it's funny, Trapper never actually had the opportunity to switch the pistol with the plunger, nor did Hawkeye or Radar.
Continuity mistake: Right after Radar tells Henry to forget about the game there's an explosion, and when Radar shouts, "More on the way!" everyone ducks and we see Henry's diploma up on the wall, but when it cuts to a different angle the diploma has vanished before the room even shakes or the heater's stovepipe falls.
Continuity mistake: While Radar's spying on Baker's hand for Hawkeye during the poker game, Baker's only wearing his T-shirt later in the game, but in the views from Radar's telescope eyepiece Baker's still wearing his jacket.
Continuity mistake: After Frank picks up the still, his hands alternate from left hand above right to right hand above left between angles.
Revealing mistake: In the swamp during the movie, Frank comes up and talks to Igor, who is running the projector. Although there is a film running, there is no film on either the supply or take-up reels.
Plot hole: When the truck with the orphans arrives, Col. Potter and Nurse Cratty greet each other like one would an old friend. Being new to Korea, Col. Potter doesn't know Nurse Cratty - as becomes clear from his reaction to Hawkeye's explanation to BJ earlier (who doesn't know Nurse Cratty for the same reason, but that's not relevant for this mistake). Note that in other parts of the series Col. Potter is depicted mostly as somewhat old-fashioned and reserved towards strangers. (00:05:20)
Factual error: Henry says that every Wednesday, his wife drives up Route 26 with some friends. US. Route 26 starts out in Nebraska and leads to Oregon. The closest thing that could be described as a "Route 26" would be the road leading from Princeton, IL to Dixon, IL which begins 85 miles from Bloomington. The writer probably meant Route 24, which passes about 20 miles north of Bloomington. (00:03:10)
Audio problem: When the soldiers in the back come flying through the window, you hear a window pane break and cullets tingle when the window is in fact a Japanese-style paper window. (00:43:40)
Dear Mildred - S4-E7
Visible crew/equipment: In the scene where BJ, Hawkeye, and Radar are in the motorcade talking about the horse, Radar is talking about how he doesn't want to give away the horse. He is standing in front of some barrels and when he moves, you can see some of the crew, the horse owner, and what looks like another horse in the background for 1 second.
Continuity mistake: Along with Radar holding an anachronistic comic book (the Avengers), the exact issue changes between wide and close shots. One has the older Avengers logo used in the '60s and very early '70s, while the second issue Radar is holding has the newer Avengers logo that just gained currency as the episode was being filmed. (00:00:45)
Requiem for a Lightweight - S1-E3
Other mistake: At the end of the show Trapper has a steak over his eye covering the black eye he received. Throughout the series the characters constantly complained about the food yet they have the audacity to waste a perfectly good steak.
Answer: Even an Army field hospital would have SOME weapons for self-defense if the enemy attacked. What's meant is that it's not a combat outfit, and therefore wouldn't have enough weapons to actually attack anyone. (It's also mentioned a few times that the Officer of the Watch is supposed to carry a pistol at all times, but Hawkeye refuses to do it when he's in charge and Colonels Blake and Potter don't enforce the rule).
Captain Defenestrator