Visible crew/equipment: When they're all in the OR talking about Aggie being at the 4077, Charles compares Colonel Potter's art style to Aggie's, and in the next shot as Potter tells the art critic to tread softly, the boom mic is visible at the top, right side of the screen and just as the mic starts to pull up the shot zooms in on Aggie.
Visible crew/equipment: While Klinger's practicing Colonel Potter's forged signature on the notepad, when BJ walks in on him and then picks up Klinger's notepad the boom mic moves across the top of the screen.
Dear Mildred - S4-E7
Continuity mistake: The injured horse that Radar, BJ, and Hawkeye go after, and who's later gifted to Colonel Potter, is played by different horses.
Continuity mistake: When Radar walks into Henry's office to tell him that there's a general there to see him, we get a good view of Henry's new desk and its beautiful ornate design, but later when Hawkeye and Trapper are carrying the desk and then it's lifted out by chopper it's a completely different desk - also note that this desk has casters.
Factual error: The announcer says that it will be the 53rd Army-Navy game, but the game has been played every year since 1890, with no games in the years 1894-98, 1909, 1917-18, and 1928-29, so this game would be number 51. Additionally, at the end of the episode we find out the result was Navy 42 - Army 36. While Navy won all three games during the Korean conflict, none of those games ended with such a score. The score in the 1950 game was 14-2.
Other mistake: When Henry is trying to convince Baker how wonderful the camp is, Henry says that they "had 'The Thing' and 'The Blob' both in one week." The movie "The Blob" was made in 1958. This season of M*A*S*H is set in 1951 and 1952 (and the war ended in 1953). (00:03:55)
Visible crew/equipment: When Frank climbs into the jeep belonging to Major General Cornell Dickering, the MPs show up at the same time that BJ and Hawkeye walk up to join the fun, and during this scene there's a T-mark (albeit a dusty one) on the ground at the driver's side of the jeep.
Continuity mistake: In an early episode Hawkeye receives a sweater knitted by his sister. Subsequently in the show he has always been an only child.
Continuity mistake: In the episode "Change of Command", Potter asks Mulcahy if he "can do Methodist". In the episode "Period of Adjustment", Potter asks Mulcahy "You wouldn't lie to a Presbyterian, would you?" Just what denomination *is* Potter?
Goodbye, Farewell, and Amen - S11-E16
Continuity mistake: Early in the episode a tank is driven into the MASH compound by a wounded soldier (demolishing the latrine in the process). The tank is an M24 Chaffee dating from the mid 1940s - it is squat and angular in shape. Later on in the episode after the tank has been hidden under a tent Hawkeye decides to drive the tank into the camp dump (demolishing the new latrine on the way). The tank has changed into an M4 Sherman - it is a lot higher and more rounded in shape.
Requiem for a Lightweight - S1-E3
Continuity mistake: The bag used by Trapper for training is marked "Property of MAJ. Frank W. Burns". However, later in the series Frank's middle name is revealed to be Marion.
Rally 'Round the Flagg, Boys - S7-E21
Revealing mistake: When Col. Flagg holds his pistol up to stop Mr. Pak Sr. from leaving, you can see there is no magazine in the pistol.
Factual error: While on the phone, Radar spells out BJ's father-in-law's last name, "H-A-Y-D-E-N" to which Hawkeye quips, "M-O-U-S-E" parodying the old line from the Mickey Mouse club. The M.M. club didn't air until 1955.
Henry, Please Come Home - S1-E9
Continuity mistake: As Henry is receiving his medal, Hawkeye walks up and stands close behind a man who is standing up and two women who are sitting down. The camera angle switches to show Hawkeye talking to Trapper and now they are standing behind two standing women. (00:03:55)
Continuity mistake: Radar hangs the hammer on the "Out of Order" sign and it is covering the 'of'. When he and Frank walk away the hammer has moved and is covering the 't' (00:15:20)
Continuity mistake: The psychiatrist is called Milton Freedman in this episode and Sydney Freedman in all other episodes in which he appears (always being played by the same actor - it is the same psychiatrist).
Continuity mistake: When Radar is slipping the glass of milk into Buzz's tent, we see the outside of the tent and there are no windows. From the inside, the milk is placed on a table that is right under a window. Also, the milk is already on the table in a scene before Radar puts it there. (00:13:20)
Answer: Even an Army field hospital would have SOME weapons for self-defense if the enemy attacked. What's meant is that it's not a combat outfit, and therefore wouldn't have enough weapons to actually attack anyone. (It's also mentioned a few times that the Officer of the Watch is supposed to carry a pistol at all times, but Hawkeye refuses to do it when he's in charge and Colonels Blake and Potter don't enforce the rule).
Captain Defenestrator