Visible crew/equipment: After Charles confronts Choi Sung Ho about the candy, Ho explains that he sold it on the black market to buy real food, and when Ho reenters the mess tent through the side door, we can see that outside there's a director's chair, which actors also use, with something printed on its back.
Visible crew/equipment: In the opening scene where General Clayton is explaining the 4077 to the psychiatrist, the scene changes to the outdoor set and the camera pans to the right. As the camera pans past the hospital, a white 1970s era shuttle van can be seen driving into the set in the upper right corner of the screen. (00:01:35)
Goodbye, Farewell, and Amen - S11-E16
Other mistake: How did Hawkeye Pierce, a surgeon, know how to drive a tank? It is nothing like driving a car and takes skills, training and experience that a surgeon simply would not have. He wouldn't even be able to start the engine.
Character mistake: When Henry is describing the fishing reel he bought for his girlfriend, he said, "with jeweled escarpment" actually it is a 'jeweled esCAPEment" not esCARPment. An escarpment is a long slope off a plateau. An escapement is a latch/release mechanism that you would find on a device like a fishing reel.
Factual error: In surgery Trapper John is singing Frank Sinatra's version of "I got you under my skin". Although it was written in 1936, Sinatra did not release it until 1956, after the Korean War ended. The 1936 version sung by Al Bowlly sounds nothing like the version Trapper John was singing, which was mimicking Sinatra's version.
Suggested correction: While it hadn't been released on vinyl until 1956, Sinatra had sung the song as early as 1946 on his radio show and during live shows.
The version Frank Sinatra sang on his radio show was similar to the original version used in the movie "Born to Dance" (a movie he references before singing his two songs). He didn't change it to the big band version that Trapper imitates until 1956.
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.
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.
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.
Plot hole: Hawkeye calls a number of people into the mess tent over the PA - the ones he allegedly suspects of being behind the thefts he is suspected of himself. Interestingly enough, Ho Jon, later revealed to be the guilty party, is not on Hawkeye's list - yet he shows up uninvited, just to be ensnared by Hawk's clever ploy. Note also that he had no way of knowing what the purpose of the meeting was, so we cannot ascribe to him the motive of wanting to find out how much Hawkeye knew.
Suggested correction: Of course Ho-Jon would come to the tent; it makes perfect sense, since he is the "houseboy" of the Swamp and, consequently, a sort of personal assistant to the Swampmen (Hawkeye, Trapper, and Spearchucker). He simply followed Trapper and Spearchucker to the tent after the announcement, probably figuring they might need him in some way.
It's late evening. It's, as far as anyone knows, an official meeting. Ho Jon isn't "standing attendance", he's sitting at the table (which is very convenient for him to hide his hands later). If he WERE standing attendance, it would be the only time in the series he does so in the mess tent instead of the swamp. It would also be the only time he's attending a meeting anyone called. Also he isn't a "house boy" - that would be totally out of character for Hawkeye, see "The Moose" - he's more an adoptee and roommate who makes himself useful. And last but not least: What a convenient coincidence, that just the guy who turns out to be the culprit would turn up uninvited, because he "might be needed" instead of staying the hell away because he is guilty and suspicious of the whole affair! Had - HAD, which he hasn't - Trapper said "Ho Jon, you better come too", you could call it a Deus Ex, but the way it is, it's just a plot hole, to quote Margaret Houlihan, "period, end of sentence."
For the Good of the Outfit - S2-E4
Factual error: During Henry Blake's command, a model of a Bell UH-1 'Huey' can be seen hanging from the ceiling of the commander's office in several shots. In fact, the Huey's first flight was only in 1956.
Factual error: Radar gives the location of the battle as Longitude 70, Latitude 27. This means the Korean war has spread to India. (00:21:00)
Continuity mistake: In the first episodes, Col. Blake's wife is named Mildred, later her name is changed to Lorraine. (In case of confusion, when Col. Potter came to the 4077th, his wife was also named Mildred, but that's not relevant).
Continuity mistake: In the first season of M*A*S*H, Hawkeye mentions that his father lives in Vermont, in the later seasons his father lives in Crab Apple Cove, Maine and has never left there in 30 years.
Continuity mistake: At one time, Col. Potter talks about how his daughter is an only child. In a different episode, he mentions that his son's wife is having a baby.
Visible crew/equipment: When Klinger's at Little Chicago he asks one of the black market vendors about cameras and he points to another vendor, and when it cuts to the next shot we can see the actor's T-mark on the ground where the man walks away (his foot even moves the T-mark) and Klinger is about to stand.
Visible crew/equipment: After Colonel Potter gets off the phone, he tells Klinger about Torgy Porgy and how after four years of medical school Torgy washed out, and just as Potter and Klinger stand up lighting equipment can be seen at the top right side of the screen.
Continuity mistake: There are two sets of the 4077 compound - the outside Fox Ranch set located at Malibu Creek State Park, and the second set inside the studio's Stage 9. The layout of both sets are quite different - Studio 9's set was vastly smaller than the Ranch set, so things such as the proximity of the Swamp to the mess tent are different between the shots filmed at the Ranch and shots filmed at Studio 9, when seen within the very same episodes.
Visible crew/equipment: When Colonel Potter and Charles exit the mess tent carrying the trays, so they can serve breakfast in bed to the winners, they split up and as Charles walks to the Swamp saying, "What a shame to have wasted all these years as a doctor," we have a great view of the boom and boom mic at the left side of the screen as it moves backwards away from Charles, outside the Swamp.