Visible crew/equipment: When Colonel Potter and Charles exit the mess tent carrying the trays, so they can serve breakfast in bed to the winners, they split up and as Charles walks to the Swamp saying, "What a shame to have wasted all these years as a doctor," we have a great view of the boom and boom mic at the left side of the screen as it moves backwards away from Charles, outside the Swamp.
Visible crew/equipment: After Margaret and BJ win the bridge game, just as Charles stands up we can see the top of the Officers Club set, and we see it again when Klinger tells Father Mulcahy, "Everyone bet on either Potter or Winchester."
Visible crew/equipment: After Hawkeye shows the photo of his father to the North Korean, when it cuts to the shot in the Officers Club just as Klinger says, "And these players you can't tell anything," the shadow of the boom mic can be seen moving at the top, right corner of the screen.
Visible crew/equipment: At the start, when BJ calls Hawkeye "twinkle toes" before Hawkeye leaves, the edge of the Swamp set can be seen at the top, left 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