Comrades in Arms: Part 2 - S6-E13
Visible crew/equipment: While Margaret and Hawkeye are hiding under the mat, just as the armed North Korean collapses to the floor the shadow of the moving boom mic is visible on the wall.
Comrades in Arms: Part 2 - S6-E13
Other mistake: During the surgery, after Hawkeye and Margaret reach the 8063rd, Margaret is explaining the procedure. She says that they are using a new vascular clamp designed at the 4077th. It appears that this is the clamp designed and built three episodes later in episode 16 "Patent 4077."
Comrades in Arms: Part 2 - S6-E13
Audio problem: When Hawkeye and Margaret are being driven into camp, everybody is cheering. Watch the driver of the jeep. He hits the horn button a number of times, but the horn is never heard.
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