Revealing mistake: As the first chopper lands on the pad, you can see that the pilot is Cowboy, a clear reuse of the shot from the episode "Cowboy"
Revealing mistake: As Hawkeye calls for quiet in the officers' club, Henry pulls the tonearm off the record player, it comes away trailing a long wire behind it. Why would it even have a long wire to trail? After all, wire costs money too. It's not like the tonearm is designed to come off and be used remotely. My guess is: they lengthened it, so the shot could be taken several times without repairing the record player every time. Now, WHY they would do it that way and not simply use a dud record player is beyond me. (00:20:55)
Revealing mistake: When the tent roof caves in and the projector shorts out in a gush of water from above, you can see that actually the projector "shorts out" before the tent roof ruptures. The crew probably didn't want to risk the pyrotechnic devices getting wet. (00:02:25)
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.
Adam's Ribs - S3-E11
Revealing mistake: As Radar, Henry, Klinger and Trapper get up to answer the emergency call, the outside background can be seen in the upper right corner of the shot, showing it was done on a sound stage.
Revealing mistake: The sound of crew making an explosion with their mouth as a cue can be heard just before the actual audio of an explosion plays.
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.
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