Anachronisms: Hawkeye can been seen in 1980s footwear in a couple of episodes.
Anachronisms: Many of the references to films and comics mention titles that appeared well after the Korean War.
Continuity: In one of the early episodes, Henry Blake refers to his wife as "Mildred". However, in later episodes her name is Lorraine. Col. Potter's wife's name is Mildred.
Continuity: Col. Potter's horse Sophie changed sex throughout the series.
Continuity: Colonel Potter enters the series as a Methodist and is a Presbyterian just after Radar goes home.
Anachronisms: In one episode, Hawkeye calls Col. Flagg a khaki Godzilla. The movie, Gojira, didn't come out until 1954 and the American version wasn't released until 1956.
Continuity: Many of the characters' backgrounds i.e. family changes from episode to episode.
Revealing mistakes: Powerlines are visible in the background of some exterior shots.
Continuity: Throughout the entire series, the nurses referred to as "Baker" have been different women, including one (in contrast) black woman, some (in contrast) single women, and a married one, whose husband Tony spends the night with her in Hotlips' tent.
Anachronisms: In one early episode Trapper and Hawkeye walk into Henry's office and a small model of a "Huey" helicopter can be seen hanging in the corner. This was the workhorse during Vietnam-not Korea.
Anachronisms: Velcro used on the blood pressure monitors. Velcro was patented in 1955.
Continuity: Dates jump back and forth during the series. Many early episodes featuring Trapper John and Henry are set in 1952 or 1953, while others with Col. Potter and B.J. are set in 1950 or 1951.
Revealing mistakes: Two sets of the camp were built, one in the outdoors, and one within a studio. This is apparent in numerous episodes when the characters are standing "outside" in broad daylight, but each cast member has numerous shadows as a result of studio lights shining in different directions, as well as an echo within the studio that is not audible on the outdoor set.
Continuity: BJ's daughter Erin's age is constantly jumping back and forth. When he first arrives, he explains that he received his orders to report after returning home with his wife from their first night out after Erin was born. When Radar leaves, Erin is big enough to walk up to Radar and call him "Daddy." In the next season, BJ explains that on his last anniversary, Peg was still 8 months pregnant with Erin, which would make her less than 1 year old. A few episodes later, Erin is once again talking in full sentences and is nearly 2 years old.
Continuity: In Harry Morgan's first season as Colonel Potter his only child is a son whose wife has a daughter. However, by the end of the series his only child has become a daughter and her husband visits Col Potter at the 4077.
Errors in geography: In the early seasons, Vietnam-like references were often made by characters: Claiming their location was in "Southeast Asia" (Korea is in northeastern Asia) and searching for missing colleagues in "the jungle" (there are no jungle regions in Korea).
Continuity: In early episodes, Margaret's father is deceased. However, later in the series her father "Howitzer Al Houlihan" actually visits the 4077.
Revealing mistakes: In the opening credit scenes of the early episodes it appears that the helicopters are flying backwards.
Continuity: Hawkeye's background and family situation changes quite a bit during the run of the series. At the beginning he is from Vermont, both parents are living, he has a married sister that sends him an oversized homemade sweater, and a nephew. By the end of the show, he is from Crabapple Cove, Maine, and he is an only child whose mother died when he was about 10.
Continuity: Although the Korean war lasted slightly over than three years (Summer of 1950 through Summer of 1953), MASH seemed to pack at least four or five Christmases throughout its run. Of specific note: Dear Dad - 1972, Dear Sis - 1978, Death Takes a Holiday - 1980, Twas the Day After Christmas - 1981.
Continuity: Several of the characters had multiple variations on their names during the series, perhaps none more so than Father Mulcahy. His name is given at various points as John, John P., Francis, Francis John Patrick, and John Patrick Francis
Errors made by characters (possibly deliberate errors by the filmmakers): In one episode, Col. Potter remarks "...and they called WWII the big war." Actually, WWI was called "The Big War"
Anachronisms: During one scene in Col. Potter's office, Col. Potter is spelling someone's name on the telephone. Hawkeye, standing nearby, responds by chanting "M-O-U-S-E" - part of the "Mickey Mouse Club" show's theme song. The "Mickey Mouse Club" did not debut on television until October 3, 1955, more than two years after the ceasefire that ended the fighting in Korea.