Visible crew/equipment: When Hawkeye removes BJ's Captain rank bars from his uniform and then pins it on Radar's knit cap, in the shot facing Hawkeye and BJ the shadow of the boom mic moves across Radar's back.
Continuity mistake: After speeding past the checkpoint Hawkeye's stopped by the MPs, and when the lieutenant takes hold of one of Hawkeye's dog tags he's holding the one on the extender chain, but next shot he's holding the other dog tag, with the extender chain and second dog tag hanging down.
Visible crew/equipment: When Hawkeye and Radar are in the jeep heading to Kimpo Air Base they drive past the checkpoint, and in their closeups the camera casts a shadow on the hood of the jeep.
Adam's Ribs - S3-E11
Revealing mistake: While Hawkeye's in the mess tent leading the protest shouting "we want something else" he climbs the tent pole, and in two of the wideshots the camera has panned a bit too far to the right, and we can see the edge of the tent facade set at the top right corner of the screen.
The Trial of Henry Blake - S2-E8
Continuity mistake: When Radar walks into the Swamp to sell wingtip shoes to Hawkeye, the dartboard isn't hanging on the door, but in two of Radar's closeups we can see part of the door with the dartboard on it.
L.I.P. (Local Indigenous Personnel) - S2-E7
Continuity mistake: After Lieutenant Willis wakes up in the Swamp he gets dressed and puts his tie around his neck with its tail end on his right, but when it cuts to his closeup the tie's wide end is at his right side, then it switches again.
Continuity mistake: When Hawkeye's saying goodbye to the nurse in the morning, he reads "35591715" from her dog tag and says, "Even your number is pretty," and then he makes another date with her and again reads her dog tag, but now the number's "39591715."
Visible crew/equipment: While Margaret's reading the story of 'The Three Bears' to Kim, just as Frank walks into the tent the curved chalk foot mark can be seen on the floor.
Other mistake: When Hawkeye and Trapper are arguing with Henry about not sending the little boy to the orphanage, Henry says, "Look, you think I wanna send this little fella away? I got two kids of my own. I'm a former child myself," but at the end of season 1 Henry's wife delivered a boy, whom Henry was aching to be with, so Henry really has three kids.
Dr. Pierce and Mr. Hyde - S2-E5
Continuity mistake: After Hawkeye and Trapper leave the OR, when they open the door to the Swamp the dartboard is not hanging on the door, but in the interior shot the dartboard's there.
Visible crew/equipment: After we hear General Clayton in the voiceover talking about how it sometimes seems like Henry is Radar's clerk, during this scene in Henry's office we can see the shadow of moving film equipment - likely the boom, at the top, left side of the screen.
Visible crew/equipment: Right after the opening credits, in the first shot as the words "Directed by Jackie Cooper" appear onscreen, the shadow of the moving boom mic can be seen at the top, left side of the screen.
Other mistake: While the dentist is working in Henry's mouth Frank's describing Hawkeye and Trapper's pranks, and right after we see a shot of the dog licking hamburger from Frank's ear, when it cuts to Henry saying, "Frank, just leave my married life out of this. Doc, will you watch it before I swallow your watch!" keep your eyes on Larry Linville as he mouths McLean Stevenson's lines along with him.
Other mistake: When Hawkeye walks into the shower tent while Ugly John's showering he removes his robe, and just as Hawkeye swings open the door to step into the shower stall we can see that he's wearing something, presumably a swimsuit.
Continuity mistake: In the mess tent, after Radar uses the ketchup he puts the cap back on, but while Hawkeye and Trapper tease Radar about his hearty appetite, when it cuts to Radar's closeups the cap is off the ketchup, but then it's back on in the wideshot.
Continuity mistake: After the opening credits it cuts to Hawkeye, Trapper, Radar, and Ugly John playing poker in the Swamp and they're all wearing their uniforms when they run out to the incoming choppers, but what we see next is the same footage from the Pilot that's shown in the opening credits, with Hawkeye and Trapper wearing Hawaiian shirts as they meet the choppers.
Continuity mistake: During the charity no-talent night, when the curtain opens on the Swinging Surgeons we can see Radar using a set of brushes on the drums, but in Radar's closeups he's using drum sticks, then in the wideshot it's back to the brushes again.
Love Story - S1-E14
Visible crew/equipment: After Radar tells Margaret that she's needed in the post-op ward Frank sneaks toward Margaret's tent, and when it cuts to Margaret walking into post-op, at the start of the shot we can see the two actors' curved chalk foot marks on the floor.
Love Story - S1-E14
Other mistake: After Hawkeye asks, "Radar who?" while he's kissing a nurse, it cuts to Trapper, Radar, and Hawkeye walking past a jeep parked in front of the mess tent, then another jeep shows up with Lieutenant Anderson, but both jeeps have the same stain (looks like rust) on the front bar - the same jeep was used in both shots.
Continuity mistake: When Hawkeye and Eddie are dancing in the Swamp, after Hawkeye sits on the hot heater Eddie knocks over the tray of glasses and the mug, but next shot the mug is back up on the table.
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