Continuity mistake: In the Swamp, Pak pulls out a stack of money, holding it by the end. In the closeup, he is holding it by the middle.
Continuity mistake: On The Bus, as Hawkeye raises Mrs. Kwang's legs for delivery, Radar is turning around, hiding his face. In the close up, Radar turns around again.
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