Visible crew/equipment: While Trapper and Hawkeye are already in Henry's office Radar and Henry walk in, and just as Henry says, "Everything in this country disappears except me," the shadow of the boom mic can be seen moving across the wall at the top right side of the screen.
Factual error: When Winchester is shown in the Post Op, his oak leaf and medical symbols are on the wrong lapels.
Continuity mistake: While Charles is reading the letter about his nephew being discharged because of fainting spells, Klinger feigns a fainting spell falling forward onto Hawkeye's cot, and his body lies lopsided with his leg hanging off, but when it cuts to the next shot Klinger's perfectly positioned on the cot. Also, note the mail Klinger tossed earlier onto Hawkeye's cot, near his pillow, is now neatly tucked under the blanket towards the foot of the cot.
Continuity mistake: While Charles, BJ, and Hawkeye are in the Officers' Club, when Margaret storms in and starts yelling at Charles about the visiting pervert Colonel, Charles facepalms himself with his right hand, but next shot his left hand is up, and it continues to switch.
Follies of the Living - Concerns of the Dead - S10-E10
Continuity mistake: When BJ, Charles, and Hawkeye are in the Swamp getting drunk they toast to "war, the fountain of loveliness," and Charles attaches the surgical clamp to BJ's hand and it dangles with the end facing out in the closeup, but the clamp faces the opposite way in the wideshot, then it's changed again.
Communication Breakdown - S10-E6
Continuity mistake: When Charles leaves the shower with newspaper covering his privates, the newspaper at his backside is wrinkled and messed up when he enters the Swamp in the exterior shot, but next shot the papers are different and arranged neatly.
Visible crew/equipment: At the start, when BJ calls Hawkeye "twinkle toes" before Hawkeye leaves, the edge of the Swamp set can be seen at the top, left corner of the screen.
Revealing mistake: During the melee at Rosie's, after Klinger gets his money and jewelry back from the cheats a guy is thrown through windows, and though we hear the sound of smashing glass we see the shreds of plastic fluttering.
Peace on Us - S7-E2
Continuity mistake: When Hawkeye, Charles, and BJ are in the Swamp, Hawkeye starts his roll about being sick of green, and by the time he heads outside and talks to Margaret the blood splatter on his surgical gown changes.
Revealing mistake: When Margaret whistles for the "third wave" she places Winchester's French horn on the ground, and there are three shots facing the jeep as it closes in on the horn - in the first two shots the horn's normal, but in the last shot the horn's already semi-squashed before the jeep even runs over it.
Continuity mistake: After Radar leaves the message with Stevens for Hawkeye's friend on the Essex, it cuts to Klinger removing a nut from the jeep and he's holding the wrench with his thumb at the top, but next shot he's holding the wrench the opposite way.
Continuity mistake: In the Operating Room, as Charles hears that his phonograph has been "donated" for use during the emergency, he turns his head from left to right. In the close up, he lifts his head.
Visible crew/equipment: When Margaret listens in on Frank's phone conversation with his wife, Margaret throws a chair at him and storms out of the office, and after she calls Frank a chinless chipmunk a boom mic dips into view at the top, left corner of the screen.
Dear Mildred - S4-E7
Continuity mistake: When Colonel Potter's in his office finishing up his letter to Mildred, right before Margaret, Frank, and the others walk in, the things on his desk change their positions between shots - such as the paper tray moving from Potter's left to the right side of his desk.
As You Were - S2-E20
Revealing mistake: At the end, in the shot of Klinger singing while he's sewing a dress on his White Rotary sewing machine, as he's guiding the fabric forward it isn't actually under the machine's presser foot, which it needs to be in order to be stitched by the needle.
As You Were - S2-E20
Continuity mistake: When Klinger's in Father Mulcahy's tent he pulls up a chair and when he sits down he places his purse on his lap, but in the closeup the purse strap is now around his left arm.
Adam's Ribs - S3-E11
Continuity mistake: While Hawkeye leads the protest in the mess tent shouting "we want something else," there are two closeup shots of the table where Klinger and Radar are seated, and Klinger's white evening purse is missing, but in the previous and following wideshots the purse is hanging on his arm.
Adam's Ribs - S3-E11
Continuity mistake: When Hawkeye's in the mess tent holding the food tray the succotash is on the left and potatoes on the right with a space in the middle, so when Igor serves him creamed corn offscreen the corn should be between the potatoes and succotash, but when Hawkeye's having the fit and walks away from Igor, the potatoes (a higher mound) are now in the center space between corn and succotash.
Continuity mistake: During Henry's home movies of Molly's birthday party, Lorraine brings out the cake with candles and sets it on the table, but the cake differs between the shots - note the writing.
For the Good of the Outfit - S2-E4
Continuity mistake: Hawkeye mails a letter to his father which is delayed in its delivery, and when Hawkeye finally receives a reply from his father it's dated May 24, 1951, but in the previous episode "Radar's Report" the weekly report that Radar typed up was dated October 17 through October 22, 1951.
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