Other mistake: When Hawkeye has Lt. Dish draw the winner of the raffle, he turns the bottom of the glass towards the crowd - meaning they would be able to see Lt. Dish pick the raffle ticket that has been taped to the bottom of the glass, just like the audience does.
Continuity mistake: In the pilot episode when Hawkeye and Trapper are going to send Ho Jon to the states to go to medical school, Hawkeye says Ho Jon can stay with his parents, but throughout the rest of the series Hawkeye's father is a widower. (00:07:50)
Continuity mistake: When Hawkeye and Trapper are arrested by Hammond at The Party there is a large crowd of people behind the General and Henry. When we cut to the shot of Margaret and Frank approaching, there is no-one in sight. (00:21:20)
Continuity mistake: After Frank picks up the still, his hands alternate from left hand above right to right hand above left between angles.
Audio problem: The original "gin machine" is entirely metal, but when Frank throws it on the floor, you hear porcelain breaking.
Continuity mistake: This episode has the heater in Henry's office in front of the window, and the wall by the window blank. Later the stove is by the window, with the diploma by the stovepipe.
Factual error: In the Swamp, Frank is complaining about everything, and goes to grab the still. The stove it's sitting on is a Coleman model 413E camping stove, a unit not seen until 1954, and the series takes place in 1950.
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