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.
Hot Lips Is Back in Town - S7-E19
Factual error: In the beginning, you can see that there's a First Lieutenant bar on Margaret's left collar instead of the medical symbol Caduceus, like Charles has on.
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