Continuity mistake: In some shots the Spam lamb has mashed potato eyes and a carrot mouth, in others it has green grape eyes and no obvious mouth, and it keeps changing. (00:23:10)
Continuity mistake: In the shot where Hawkeye presents the Spam lamb to Henry, he sets it down, and Henry asks him what it is. Behind Henry, you can see Hawkeye's shadow - and see his lips mouth the word "A Spam lamb". The camera then changes to a close-up of Hawkeye, saying "A Spam lamb".
Continuity mistake: When Radar goes to get the lamb, he pulls out a hypo to put the lamb to sleep for shipping. When the shot cuts to the lamb, you can see both of Radar's hands on the lamb's face; no hypo in sight.
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