Visible crew/equipment: After Charles confronts Choi Sung Ho about the candy, Ho explains that he sold it on the black market to buy real food, and when Ho reenters the mess tent through the side door, we can see that outside there's a director's chair, which actors also use, with something printed on its back.
Visible crew/equipment: In the opening scene where General Clayton is explaining the 4077 to the psychiatrist, the scene changes to the outdoor set and the camera pans to the right. As the camera pans past the hospital, a white 1970s era shuttle van can be seen driving into the set in the upper right corner of the screen. (00:01:35)
Factual error: When Klinger's walking with Captain Allen and the Stars and Stripes photographer, just before their introductions to "Ben" they pass an empty corrugated box with its flap open, and the recycling symbol can be seen on the flap. Recycling symbols were not in use until about 20 years later.
Other mistake: When Henry gives Leslie the gift he says, "I sent to Tokyo for this... A Sato Tanaka double-cammed reel with jeweled escarpment," and we can see on different sides of the box there's green tape hiding its brand name, "Penn," though we can still make out the "Beachmaster 155" name.
Other mistake: When Frank's with Margaret in her tent and she tells him that she thinks they should reevaluate their friendship, there's a Life Magazine lying on her bed which is dated over 15 years in the future - August 25, 1967, with "The other war in Vietnam" written on its cover.
Snap Judgment (Part 1) - S10-E7
Visible crew/equipment: When Klinger's at Little Chicago he asks one of the black market vendors about cameras and he points to another vendor, and when it cuts to the next shot we can see the actor's T-mark on the ground where the man walks away (his foot even moves the T-mark) and Klinger is about to stand.
Visible crew/equipment: After Colonel Potter gets off the phone, he tells Klinger about Torgy Porgy and how after four years of medical school Torgy washed out, and just as Potter and Klinger stand up lighting equipment can be seen at the top right side of the screen.
Visible crew/equipment: When Colonel Potter and Charles exit the mess tent carrying the trays, so they can serve breakfast in bed to the winners, they split up and as Charles walks to the Swamp saying, "What a shame to have wasted all these years as a doctor," we have a great view of the boom and boom mic at the left side of the screen as it moves backwards away from Charles, outside the Swamp.
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.
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.
Welcome to Korea (60 mins.) - S4-E1
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.
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.
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: 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)
Continuity mistake: In some shots, Radar's exam questions are in his hand, in others they are tucked under his arm. (00:10:30)
Welcome to Korea (60 mins.) - S4-E1
Continuity mistake: When Radar and Burns leave the tent for morning parade, Radar's clipboard acquires a pencil. (00:02:50)
Visible crew/equipment: When Frank and Hot Lips are walking into the mess tent for Frank's surpise party, if you look in the window to the right of the door, you can see a person silhouetted, throwing leaves into the wind.
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.