Other mistake: When Frank's with Margaret in her tent and she tells him that she thinks they should reevaluate their friendship, there's a Life Magazine lying on her bed which is dated over 15 years in the future - August 25, 1967, with "The other war in Vietnam" written on its cover.
Other mistake: Near the end of the episode Hawkeye is finishing his letter to his father. He writes "kiss mom and sis", but later in the series we find out that his mother died when he was a kid and he doesn't have any siblings.
Other mistake: When Henry gives Leslie the gift he says, "I sent to Tokyo for this... A Sato Tanaka double-cammed reel with jeweled escarpment," and we can see on different sides of the box there's green tape hiding its brand name, "Penn," though we can still make out the "Beachmaster 155" name.
Requiem for a Lightweight - S1-E3
Other mistake: At the end of the show Trapper has a steak over his eye covering the black eye he received. Throughout the series the characters constantly complained about the food yet they have the audacity to waste a perfectly good steak.
Other mistake: During the game, when the second bomb goes off, the whole building is shaking and things are falling all around but the drinks on the table do not move at all.
Sometimes You Hear the Bullet - S1-E17
Other mistake: Wendel, afraid of being shipped home, is trying to escape from the MASH by hot-wiring a Jeep. Despite just having had an appendectomy, he is leaning forward and to the right from a sitting position, which would have to put pressure directly on the incision, yet when discovered by Hawkeye, he easily and without discomfort sits up straight. Aside from him still being at the MASH, we know the surgery is recent because, just a little later, he winces and complains after making a very small movement.
Other mistake: While the dentist is working in Henry's mouth Frank's describing Hawkeye and Trapper's pranks, and right after we see a shot of the dog licking hamburger from Frank's ear, when it cuts to Henry saying, "Frank, just leave my married life out of this. Doc, will you watch it before I swallow your watch!" keep your eyes on Larry Linville as he mouths McLean Stevenson's lines along with him.
Other mistake: When Hawkeye walks into the shower tent while Ugly John's showering he removes his robe, and just as Hawkeye swings open the door to step into the shower stall we can see that he's wearing something, presumably a swimsuit.
Love Story - S1-E14
Other mistake: After Hawkeye asks, "Radar who?" while he's kissing a nurse, it cuts to Trapper, Radar, and Hawkeye walking past a jeep parked in front of the mess tent, then another jeep shows up with Lieutenant Anderson, but both jeeps have the same stain (looks like rust) on the front bar - the same jeep was used in both shots.
Henry, Please Come Home - S1-E9
Other mistake: While Radar's in post-op waiting for Henry's arrival he's seen reading Marvel Comics "Captain Savage and His Battlefield Raiders!" issue #10, published January 1969. It's one of the 19 issues in this comic book series which were originally named "Captain Savage and His Leatherneck Raiders," and it ran from 1968 until 1970, many years after the Korean War ended. This comic is also seen in the episode "Tuttle" later this season.
Other mistake: At the end, after General Barker tells Henry that he should give Frank a high colonic and send him on a 10 mile hike, Klinger shows up in front of them supposedly naked, but we can see the top of whatever the actor's really wearing.
Other mistake: When they're playing poker, Hawkeye is sitting at an angle so that Sgt. Baker cannot see the earpiece that Hawkeye is wearing. However, Hawkeye sometimes turns his head enough for us to see his ear and, since the camera angle is over Baker's shoulder, Baker must have been able to see the earpiece too and realise he was being cheated. (00:13:20)
Other mistake: While playing golf, something blows up Henry's golf ball. When the camera does a closeup on Henry's ball, you can see that it isn't a golf ball, but a prop designed to blow up.
Other mistake: As Hawkeye sings in the Swamp to mock Frank, watch Trapper. He's miming the words until his cue to join in.
Other mistake: Hawkeye reads the propaganda flyer, he says. "Give yourselves up, you can't win. Douglas MacArthur." Trouble is, the papers are all advertising for a flying company called Ace Eli.
Other mistake: In this episode Max is wearing a red bandanna that he says "My mom gave me this when I shipped out. She said never take it off." However, in no episode before or after this does this good luck charm appear.
Other mistake: Hawkeye loosened the nut and locking ring, but after lifting the assembly, it was obvious that these were steps used only to heighten tension. There was no locking device of any kind between the tail and body of the bomb.
Other mistake: After Klinger gives the long johns to Mulcahy, he "disappears." But if you look closely through the camo net, you can see him in the shadows of the background.
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