Peace on Us - S7-E2
Revealing mistake: Klinger says "The sun is going to ruin my comb-out", fingering his hair net. He has curlers under his hair net, but his hair is not around the curlers, they're just stuffed into his hair net. (00:01:10)
Peace on Us - S7-E2
Revealing mistake: When Colonel Potter's in the Swamp telling Hawkeye, BJ, and Charles that surgeons' rotation points have increased from 36 to 45 Hawkeye becomes incensed, and in these two shots from this angle we can see the edge of the Swamp set at the top, left corner of the screen.
Revealing mistake: When Hawkeye exits the tub, you can see his shorts as he wraps the towel around himself.
Revealing mistake: In the first scene, when the camera pans back, in the upper left corner of the screen you can see that a part of the tent has been removed to make room for the camera. (00:02:15)
Revealing mistake: When Hawkeye and BJ are in the showers and Margaret steals their towels and clothes, the duo head back to the Swamp naked, but we can see the top of whatever Hawkeye's wearing.
Revealing mistake: When the ambulance arrives in the compound at Christmas eve, it drives through the newly fallen snow, but it doesn't leave any tracks. Vehicles driving over a very thin snow cover always leave dark tracks, because the pressure instantly melts the snow just below the wheels. Even a person walking through the snow would leave dark footprints under these conditions.
Hot Lips Is Back in Town - S7-E19
Revealing mistake: While Hawkeye's in the shower Radar shows up with a cup of coffee, and when Hawkeye steps out of the shower stall the door swings out so we can see the top of whatever Hawkeye's wearing.
Rally 'Round the Flagg, Boys - S7-E21
Revealing mistake: When Col. Flagg holds his pistol up to stop Mr. Pak Sr. from leaving, you can see there is no magazine in the pistol.
Rally 'Round the Flagg, Boys - S7-E21
Revealing mistake: As Charles leaves the Mess Tent, you can see the camo net where there normally is none, and the background abruptly ends about 20 feet from the end of the building.
Revealing mistake: During the melee at Rosie's, after Klinger gets his money and jewelry back from the cheats a guy is thrown through windows, and though we hear the sound of smashing glass we see the shreds of plastic fluttering.
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