Peace on Us - S7-E2
Revealing mistake: When Colonel Potter's in the Swamp telling Hawkeye, BJ, and Charles that surgeons' rotation points have increased from 36 to 45 Hawkeye becomes incensed, and in these two shots from this angle we can see the edge of the Swamp set at the top, left corner of the screen.
Adam's Ribs - S3-E11
Revealing mistake: While Hawkeye's in the mess tent leading the protest shouting "we want something else" he climbs the tent pole, and in two of the wideshots the camera has panned a bit too far to the right, and we can see the edge of the tent facade set at the top right corner of the screen.
Revealing mistake: While Hawkeye and Eddie are in the Swamp, when Eddie knocks over the stovepipe we can see that it's actually split into two pieces for the stunt, whereas in the previous shots it's not.
Adam's Ribs - S3-E11
Revealing mistake: As Radar, Henry, Klinger and Trapper get up to answer the emergency call, the outside background can be seen in the upper right corner of the shot, showing it was done on a sound stage.
Rally 'Round the Flagg, Boys - S7-E21
Revealing mistake: As Charles leaves the Mess Tent, you can see the camo net where there normally is none, and the background abruptly ends about 20 feet from the end of the building.
Revealing mistake: In several supposedly outdoors scenes in the camp, in particular, when Frank is welcoming Margaret back, there's a very obvious indoorsy echo. (00:22:10)
Revealing mistake: When the second shell explodes outside, the shelf in the right foreground shakes a moment, then the top suddenly flips up, dumping the bottles that were on it. Obviously a stagehand flipped it when no bottles fell.
Revealing mistake: When Radar salutes Major Burns dropping the package, you can see wet spots on his uniform where he held the package. Before the bottle inside breaks, it is supposed to be dry. The crew probably re-used a single package for several takes of the shot. (00:04:45)
Revealing mistake: A number of times, during the night periods (for instance, during an OR scene) the windows are dark when the lights are on in the room. Then when the lights go out, the windows brighten up. They, and the interior lights seem to alternate lightening and darkening.
Revealing mistake: In the first scene, when the camera pans back, in the upper left corner of the screen you can see that a part of the tent has been removed to make room for the camera. (00:02:15)
The Sniper - S2-E10
Revealing mistake: When The Sniper begins his attack, a sandlot football game is in progress in the compound. As the quarterback goes back to throw a pass, he waits just long enough for the ball to be "shot" out of his hand.
Revealing mistake: As the first chopper lands on the pad, you can see that the pilot is Cowboy, a clear reuse of the shot from the episode "Cowboy"
Revealing mistake: When Sherwood has died on the gurney, with Roberts holding his hand, after breathing stops, you can see the bandage on his neck still jumping in time with his pulse.
Revealing mistake: In Margaret's tent, while she is getting ready, if you look at the central pole you can see the cut where it is supposed to break when Frank hits it.
Revealing mistake: Potter is taking the driving part of the test, with Rizzo riding along. In the long shot, as well as looking at Klinger stumbling along, you can see the Jeep occupants are stunt doubles.
Revealing mistake: Klinger makes a big show of removing a big nut from the Jeep's leaf spring. The nut is clean and shiny whereas the rest of the undercarriage is painted and dirty. If you look closely, there are no screw threads where he takes it off either, there's another hex under it. The simple reason for this is that that nut doesn't belong there and never was affixed, Jamie Farr just pretended it was.
Revealing mistake: In the supply room, as Hawkeye lights two candles, the room gets noticeably brighter. However, there's too much light for two candles, and his shadow comes from above.
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.
Revealing mistake: There is a lag between the interior lights going out and the exterior stage lights going on.
