Visible crew/equipment: When General Haggerty walks into the mess tent and stands beside Colonel Potter, the chalk T-mark can be seen on the floor near his feet, and when Haggerty wants to meet the cook the chalk mark can be seen on the floor where Conway stands.
Visible crew/equipment: After BJ and Hawkeye have tasted the Spam Parmesan, when Klinger calls the cook over, in the shot of Conway the edge of the tent set can be seen at the top right corner of the screen.
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