Where There's a Will, There's a War - S10-E16
Continuity mistake: At Battalion Aid, Hawkeye gets under a table to write. An explosion knocks two of the three stacks of cardboard boxes off the table above him. When the angle changes, there's now two stacks, where there should be only one.
Where There's a Will, There's a War - S10-E16
Continuity mistake: As Hawkeye climbs under the table to hide there are three small stacks of white bandage boxes on the table. When the shelling starts, all the boxes in two of the stacks fall off the table, leaving one stack. When the shot changes, there are suddenly two stacks of boxes on the table.
Where There's a Will, There's a War - S10-E16
Revealing mistake: When Hawkeye injects the adrenalin into the chest of the dying soldier at the battalion Aid Station, you can see that he is actually injecting into a piece of rubber foam soaked with prop blood. (00:13:25)
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