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.
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.
Factual error: As Hawkeye performs CPR on the hypothermic soldier, he pumps his arms from his ellbows. CPR is done by keeping the arms stiff and pumping with the whole upper body. Hawkeye as a surgeon would know that. Fun Fact: You can perform CPR one-handed in a pinch, but only as long as you keep your arms stiff.
Revealing mistake: While painting Winchester's portrait, the camera looks across Potter's position. As it does, the picture is totally finished, though Potter acts like he's working on it.
Trivia: After Harry Morgan joined the cast as Col. Sherman T. Potter, the character is shown numerous times painting portraits of the main characters. However, he never painted them. The studio prop master farmed out the work to local talent who was happy for the work. None of those artists have been named.
Other mistake: Charles starts a discussion on the army having forbidden the use of curare. The following chatter is all about how things in the M.A.S.H. OR have slowed after curare was banned, leaving us with no choice but to understand that the ban came into effect during the Korean War. Actually, curare was not approved for use by the U.S. Army at any time during the Korean War. (See "Notable Names in Anasthesia" - J. Roger Maltby, Royal Society of Medicine, Great Britain, pg. 14). (00:00:25)
Factual error: While eating, General Haggarty was told about how Conway should be a cook. Haggarty said "Change his (Conway's) MOS. MOS means Military Occupational Specialty, your job in service. Since M*A*S*H was set in the early 50's, Haggarty wouldn't have said that, because 'MOS' wasn't used until 1965.
Continuity mistake: In this episode, as they come from the pad, Hawkeye told them to get his canvas tub. But in "None Like It Hot", he had one that caused a lot of trouble and they traded it away for ice cream.
Other mistake: Many times during the series, soldiers are around the OR carrying a loaded weapon (magazine attached for example), when there is a sign outside the entrance that says "all weapons must be cleared before entering the building" or similar.
Plot hole: Charles has the money and family connections. Why didn't he try to get the baby girl sent to the US? Trapper and his wife almost adopted a seemingly orphaned Korean boy in an early episode, so it couldn't have been impossible.
Other mistake: As Frank cocks his gun in the Swamp, the slide locks open and he has to hit the slide release to get it to move forward. Next he fiddles with the hammer. Next we hear the shot go off. Burns' excuse later is that he was cleaning The Gun and it went off (although admittedly, Frank doesn't always stick to the truth that religiously in situations like that). The slide on a semi-automatic locks open only if the magazine is empty or missing. The Gun locking open is also a clear, unmistakable indication that the breech is empty. He would have to insert a filled mag, then pull the slide back again to chamber a round before The Gun even had the chance to go off. One never does that while cleaning a gun. One does what Frank did to begin with: Pull the slide back without a magazine inserted to make sure the breech is empty.
Character mistake: At the end of the episode, while Col. Potter is in the helicopter asking where they are, the pilot says they are about 10 miles west of Inchon. Col. Potter says this is no good and he tells the chopper pilot to "head west, towards Inchon." If they are already west of Inchon, heading west will take them further from Inchon.
Continuity mistake: When the two soldiers get into a brawl in Post-Op, it's daytime. When Potter talks to Mulcahy, it's night. Then Klinger tells Mulcahy he's needed to break up the fight, it's daytime again.
Character mistake: Hawkeye and Trapper make Tuttle an alumnus of "Berlin Polytechnic" and translate that (wrongly) as "Berlinishes Polytechnikum". Berlin's polytechnic university was named "Technische Hochschule Berlin" at the relevant time - and at no time offered a medical curriculum. To study medicine in Berlin, Tuttle would have to attend "Freie Universität Berlin" instead.