Continuity mistake: During the charity no-talent night, when the curtain opens on the Swinging Surgeons we can see Radar using a set of brushes on the drums, but in Radar's closeups he's using drum sticks, then in the wideshot it's back to the brushes again.
Love Story - S1-E14
Visible crew/equipment: After Radar tells Margaret that she's needed in the post-op ward Frank sneaks toward Margaret's tent, and when it cuts to Margaret walking into post-op, at the start of the shot we can see the two actors' curved chalk foot marks on the floor.
Love Story - S1-E14
Other mistake: After Hawkeye asks, "Radar who?" while he's kissing a nurse, it cuts to Trapper, Radar, and Hawkeye walking past a jeep parked in front of the mess tent, then another jeep shows up with Lieutenant Anderson, but both jeeps have the same stain (looks like rust) on the front bar - the same jeep was used in both shots.
Continuity mistake: When Hawkeye and Eddie are dancing in the Swamp, after Hawkeye sits on the hot heater Eddie knocks over the tray of glasses and the mug, but next shot the mug is back up on the table.
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.
Henry, Please Come Home - S1-E9
Other mistake: While Radar's in post-op waiting for Henry's arrival he's seen reading Marvel Comics "Captain Savage and His Battlefield Raiders!" issue #10, published January 1969. It's one of the 19 issues in this comic book series which were originally named "Captain Savage and His Leatherneck Raiders," and it ran from 1968 until 1970, many years after the Korean War ended. This comic is also seen in the episode "Tuttle" later this season.
Visible crew/equipment: When General Barker opens the doors to Henry's office and finds Radar sitting behind the desk, we can see Barker's curved chalk foot marks on the floor beside the desk, where the actor will stand in a moment.
Other mistake: At the end, after General Barker tells Henry that he should give Frank a high colonic and send him on a 10 mile hike, Klinger shows up in front of them supposedly naked, but we can see the top of whatever the actor's really wearing.
Continuity mistake: This episode has the heater in Henry's office in front of the window, and the wall by the window blank. Later the stove is by the window, with the diploma by the stovepipe.
Requiem for a Lightweight - S1-E3
Audio problem: When Margie is saying she is impressed, Trapper replies "I should hope so", but his mouth doesn't move.
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.
Continuity mistake: After Hawkeye and Trapper cut the bomb wires, Trapper kneels down to see if it's still ticking, and his hand disappears from his helmet. (00:23:05)
Sometimes You Hear the Bullet - S1-E17
Factual error: We see Pvt. Wendel trying to hot-wire a jeep to escape. He wouldn't have to hot-wire it, because vehicles assigned to a combat zone were equipped with an ignition switch, not an ignition lock, for the simple reason that keys get lost or mislaid all the time and in an emergency, having to track down keys for vehicles would be extremely detrimental to an unit's combat effectiveness.
Character mistake: In the opening scene, Hawkeye and Trapper are operating on a two-star general. But neither one of them or the nurse is wearing their masks. They are under their chins.
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.
Factual error: In the Swamp, Frank is complaining about everything, and goes to grab the still. The stove it's sitting on is a Coleman model 413E camping stove, a unit not seen until 1954, and the series takes place in 1950.
Continuity mistake: Casey's glasses go from dark framed to metal framed and back as he says goodbye to Hawkeye.
Love Story - S1-E14
Continuity mistake: When Trapper puts on the "Dear John" recording, the record is moving at two different speeds in the close up and wide shots.