Visible crew/equipment: When Hawkeye removes BJ's Captain rank bars from his uniform and then pins it on Radar's knit cap, in the shot facing Hawkeye and BJ the shadow of the boom mic moves across Radar's back.
Continuity mistake: After speeding past the checkpoint Hawkeye's stopped by the MPs, and when the lieutenant takes hold of one of Hawkeye's dog tags he's holding the one on the extender chain, but next shot he's holding the other dog tag, with the extender chain and second dog tag hanging down.
Visible crew/equipment: When Hawkeye and Radar are in the jeep heading to Kimpo Air Base they drive past the checkpoint, and in their closeups the camera casts a shadow on the hood of the jeep.
Continuity mistake: The "KILROY" Hawkeye writes on the window as BJ looks out was in the center with his fingertip. Later, as Hawkeye looks out, the "KILROY" is now closer to the frame, and the lettering is different, a small capital A in front of it, and lines above and below it.
The Price of Tomato Juice - S4-E15
Other mistake: Actor Jeff Maxwell plays Private Igor Straminsky, however when Maj. Burns is in line and asks for his name, he replies "Maxwell" and Burns in turn repeats the name "Maxwell", instead of "Straminsky."
Factual error: Nearing the end of the show, we are told that the Chinese have become involved in the conflict and have attacked with some 300,000 soldiers. This apparently refers to massive attacks by the Chinese starting on November 1, 1950. Although the numbers are correct, the US/UN forces were unaware of the numbers. As late as November 6, the Far East Command continued to insist that there were no more than 34,500 Chinese communist soldiers in country. http://www.history.army.mil/brochures/kw-chinter/chinter.htm.
Revealing mistake: In several supposedly outdoors scenes in the camp, in particular, when Frank is welcoming Margaret back, there's a very obvious indoorsy echo. (00:22:10)
Continuity mistake: Early in the episode it is stated that Margaret's tent door is padlocked while she is in Tokyo. But when she gets back, she just walks straight in. (00:22:20)
Continuity mistake: In the assembly called by Major Burns at the beginning of the show, Klinger is in the front rank far left (except when the continuity error has him centre rear), but after the appearance of Hawkeye in the rickshaw Klinger isn't on parade at all.
The Late Captain Pierce - S4-E4
Other mistake: When Digger shows Hawkeye the copy of the death certificate, Hawkeye steps out of the shower stall and its door swings back and forth. As Hawkeye wipes his face with the towel, we can see the top of the flesh colored covering Hawkeye is wearing. (00:08:05)
Factual error: When the can of beans explodes all over Hawkeye and Hotlips, they act as though the beans are cold. In fact the beans would have been at boiling temperature as the can overheated, causing it to explode, and the two would have been burned.
Factual error: In the hut with BJ, Zale, and The Moose, there's a Coleman 413E stove in the background. Trouble is, that this unit didn't appear until 1954, and the Armistice ending hostilities, ending the war, was signed July 27, 1953.
Factual error: When the South Korean Colonel and General are in the Mess Tent with BJ, their rank insignia is wrong. The insignia the Colonel is wearing is for a U.S. Colonel, and the General's insignia would not be three stars in a horizontal line.
Other mistake: It's 1952 when Potter arrives at the 4077. He tells Radar that he joined the army during WWI when he was 15 (he lied about his age). That would mean that Potter was 50 when he arrives. But he said that he'd be retiring in 18 months. Also, in the episode "Point of View" Potter states that this was the first time in 37 years that he missed calling Mildred for their anniversary. That would mean that Potter was 13 when he got married.
Character mistake: The last bet comes to Frank after Mulcahy bets a dollar, and Potter raises fifty cents, making it a dollar fifty. Frank makes it another five dollars, making it six dollars fifty cents. Mulcahy says "Oh dear, it's five fifty to me." He should have said six fifty.
Other mistake: When the Colonel Griswald of the 1st Cavalry goes to leave camp, the Jeep he gets in is marked "4077 MASH" on the bumper instead of 1st Cav.
Dear Mildred - S4-E7
Revealing mistake: When the camera is in a close up on Dan the pilot, the sound is a chopper that is running full power, but you can tell that the main rotors are turning slowly to simulate flight.
Answer: The C-42 was a military variant of the Douglas DC-2. Very few C-42's were built, so it's questionable that Potter would specifically have seen that particular model, but, given his military background, it's not entirely unreasonable that he might use the military designation even when the aircraft in question is actually a civilian DC-2.
Tailkinker ★