Factual error: In this episode, the regulars receive and respond to letters from a Fourth-Grade class in Hawkeye's home town. Charles receives one from a little girl who says she's sent him a birch leaf. Unfortunately, the leaf he removes from her glassine envelope is a maple leaf. (Note: there was no indication that this was supposed to be her mistake.)
Factual error: After the opening credits it cuts to Klinger at Mail Call, and Father Mulcahy's reading Ring Magazine which is dated December 1969, 16 years after the Korean War ended.
Factual error: When BJ opens the first box of tongue depressors the tongue depressors are packaged in a plastic bag inside the cardboard box, my research says that plastic bags were not available in the early 1950's. (00:08:06)
Factual error: When Klinger's walking with Captain Allen and the Stars and Stripes photographer, just before their introductions to "Ben" they pass an empty corrugated box with its flap open, and the recycling symbol can be seen on the flap. Recycling symbols were not in use until about 20 years later.
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