Continuity mistake: The psychiatrist is called Milton Freedman in this episode and Sydney Freedman in all other episodes in which he appears (always being played by the same actor - it is the same psychiatrist).
Other mistake: Radar says the weekly report is for the 17th to the 22nd inclusive. A 6 day week in the middle of a war?
Continuity mistake: When Hawkeye and Lt. Johnson are sharing Hawkeye's bottle of "wine" there's a closeup of Johnson's hand holding the glass, and in the closeup that hand has short nails, whereas in all other shots Johnson has long nails.
Visible crew/equipment: When Klinger walks into Henry's office while Margaret and Frank are there, we can see the chalk T-mark on the floor behind Margaret where Radar was standing moments ago.
Visible crew/equipment: When Dr. Freedman's in Henry's office before Klinger walks in, just as Henry says, "You're the doctor," the shadow of the moving boom mic can be seen at the top left side of the screen.
Continuity mistake: When Trapper and Hawkeye are sitting outside the Swamp, Hawkeye pours the martinis from the tall glass beaker, and in the shots facing Hawkeye there are quite a few large ice cubes in the beaker, but in the shots facing Trapper there aren't as many ice cubes floating in the beaker.
Factual error: Radar claims in his report that Father Mulchahy tried to calm the prisoner by saying "bang zhao", thinking it means "peace and friendship" when it really means "your daughter's pregnancy brings much joy to our village." There is, unsurprisingly, not even a remotely similar word in Chinese that means either of those things.
Other mistake: The Chinese patient cut the strap of Klinger's red gown, but Radar says Klinger requests a replacement brassier. Later Klinger's red gown shows no damage, although he could have retied the strap.
Continuity mistake: The amount of alcohol in the bottle Hawkeye holds in the Swamp goes from full to half empty and back between cuts.
Continuity mistake: When Hawkeye passes by Frank on his way to Lt. Johnson's, he's holding a bottle of gin up near his waist. In the next shot, his arm is resting down by his side. (00:08:30)
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