Not even M*A*S*H, with its perfect blend of comedy and drama could go eleven years without some mistakes. However, the errors which the writers and producers made do not detract from the overall quality of the show. Some fans of the show may not even realize these mistakes exist.
In "Dear Dad," Hawkeye mentions that winters are cold home in Vermont; in almost every other instance, from the book MASH to "Goodbye, Farewell, and Amen," Hawkeye's home is in Crabapple Cove, Maine. In "The Late Captain Pierce" Hawkeye tells Klinger that his house in Crabapple Cove is only a summer cottage; but in "The Party" he says his father hasn't left Crabapple Cove for years.
At the end of his letter in "Dear Dad...Again," Hawkeye says to "kiss Mom and Sis"; however, in "Sons and Bowlers" he tells Charles how his mom died when he was young. In "Hawkeye," he says that he was an only child.
Radar's character can be divided into "early Radar" and "late Radar." After the first season or two, they gradually made the character more naive and innocent.
During earlier episodes such as "To Market, To Market", "The Longjohn Flap", and "The Trial of Henry Blake" Radar is shown eating a lot of meat, including lamb chops. Then in "Private Charles Lamb" Radar tells Frank that he's a vegetarian and rescues the lamb because he couldn't stand the thought of it being killed.
Radar could be seen drinking in several early episodes such as "Tuttle" and "Chief Surgeon Who?"; however, in "End Run" from season 5, Radar takes one sip of the home-made hooch from the still and is taken by surprise. Radar is also strongly affected by a sip of liquor in "The Price" and "Goodbye Radar." Also, in the early seasons Radar smokes cigars in episodes such as "Chief Surgeon Who?" However, in "Fade Out, Fade In" Col. Potter shows Radar how to smoke a cigar for the first time.
In "Check-Up" Radar proudly shows Colonel Blake his new tattoo of a anchor. After this episode we never see this tattoo and in "Images" everyone makes a big deal out of his desire to get a tattoo. He ends up getting a tattoo of a bear on his bottom (in pen of course).
Throughout the eight years in which Gary Burghoff was on M*A*S*H, they used what appeared to be the same teddy bear. In "As Time Goes By," Hawkeye donates Radar's teddy bear to the time capsule; however, this was a different bear.
In "Movie Tonight," episode 117 during season 5, Radar does his impression of John Wayne in "McLintock," a movie which was not made until 1963.
In several episodes such as "Der Tag," Radar can be seen with comic books such as "The Avengers" and "The Amazing Spider-man" which were not in print until the 1960s or later.
The problem with the good Father and his sister is that their names change. In most episodes, his name is given as "Francis John Patrick Mulcahy"; however, in some episodes it's different. In "The Pilot" his name is given as "John P. Mulcahy"; in "Dear Sis" Hawkeye calls him "John Patrick Francis Mulcahy." Mulcahy's sister is normally referred to as "Katherine" or "Sister Maria Angelica," but in "The Most Unforgettable Characters" from season 5 she is called "Sister Theresa."
In one episode in season 9, Klinger's serial number is given with "RA" at the beginning which stood for Regular Army and Klinger definitely was not Regular Army, he was a draftee. In "Dear Sigmund," episode 103 from season 5, Klinger says, "I'd wear hula hoops in my ears..."; then in "Who Knew?" from the final season, Klinger tries to get Charles to invest in hula hoops, a new invention.
During his first meeting with Father Mulcahy in "Change of Command," Potter mentions that he is a Methodist. While speaking with Mulcahy in "Period of Adjustment" about company clerks, Potter asks him, "You wouldn't lie to a Presbyterian, would you?"
Throughout most of his stay at the 4077th, Sherman's home is in Missouri; however, in "Ping Pong" he mentions going home to Nebraska.
Potter's horse Sophie starts out as a male in "Dear Mildred" in season 4; however, after this episode Sophie is referred to as a mare (a female horse).
Colonel Potter arrives at the 4077th on September 19, 1952 in the trailer of "Welcome to Korea." In "A War for All Seasons" from season 9 he stands as the old year "1950" at the first New Year's Party and then as 1951 at the second party.
In "Dear Mildred," the Potters are about to celebrate their 27th wedding anniversary; however, in "Images" Potter mentions his upcoming 38th wedding anniversary. Then, in "Point of View" Potter says they've been married for 35 years. In "Too Many Cooks," Margaret indicates the Potters have been married for 40 years.
During early episodes such as "The Army-Navy Game," Henry's wife is named Mildred; however, later her name is changed to Lorraine such as in "Life With Father."
When Henry was sent home in "Abyssinia, Henry," they said it was because he had enough points. In reality, the Army stopped using the point system after World War II and doctors were never rotated according to points. The point system is also used during other episodes such as "The Most Unforgettable Characters" and "Peace on Us."
In "Showtime" Henry finds out about the birth of his son Andrew; however, in "Abyssinia, Henry" Andrew is already playing the horn. In "Kim" Henry says he has two kids of his own, but by that time Andrew, his third child, had already been born.
In "Hot Lips and Empty Arms" and other early episodes, Margaret says her father is dead. In "Bulletin Board" there is even mention of money which he willed to her. However, he went to the stateside party in "The Party" and comes to visit the 4077th in "Father's Day" during season 9.
During the beginning of the first season, Spearchucker Jones was the fourth inhabitant of the Swamp. The writers then dropped this character when they found out that there were no black surgeons in the Army in Korea.
In his first appearance in "Radar's Report," episode 27, Dr. Freedman is called "Milton"; however, in subsequent appearances such as in "Dear Sigmund" his name is given as "Sidney Theodore Freedman."
In "The Price of Tomato Juice," Igor, who is played by Jeff Maxwell, tells Frank his name is Maxwell. During the next season they changed Igor's last name to Straminsky.
From time to time there was mention of Godzilla, such as in "Quo Vadis, Captain Chandler?"; however, the first Godzilla movie was not made until after the Korean War.
In "The Smell of Music," episode 135, there was a slight oversight. After Colonel Potter talks Saunders out of commiting suicide with the gas mask in the O.R., they never turn off the gas before they leave O.R.
The doctors and nurses use the drug Levophed in the 8th season, but in "Birthday Girls," an episode from the 10th season, Charles demonstrates the use of the drug for the first time.
Thanks to Tim Lindblad, A. Matteson for some of the info.