As You Were - S2-E20
Revealing mistake: At the end, in the shot of Klinger singing while he's sewing a dress on his White Rotary sewing machine, as he's guiding the fabric forward it isn't actually under the machine's presser foot, which it needs to be in order to be stitched by the needle.
As You Were - S2-E20
Revealing mistake: As Henry goes over to the expectant mother, a round takes out the generator. After the lights go out, there is a blue light outside the window, and also blue lights over the action. They can be seen in the reflections on the light sets over the tables.
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