The General's Practitioner - S5-E20
Continuity mistake: Near the beginning, while Col. Bidwell is watching Hawkeye operate, in the closeups he is standing by the window but in the wide shots he is standing in a different part of the O.R. (00:04:00)
Continuity mistake: While Klinger is mending the movie, the amount of film on the two reels changes a lot between shots. (00:12:20)
Continuity mistake: After the movie breaks, Hawkeye is giving an over dramatic intro to Margaret. He has his left arm raised, and a second later, both hands are at chest level.
Continuity mistake: As Klinger waves his hands to get attention for his part, it can be seen they're empty. A second later, he has a bulb in his right hand.
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