Where There's a Will, There's a War - S10-E16
Continuity mistake: At Battalion Aid, Hawkeye gets under a table to write. An explosion knocks two of the three stacks of cardboard boxes off the table above him. When the angle changes, there's now two stacks, where there should be only one.
Are You Now, Margaret? - S8-E2
Continuity mistake: After Hawkeye, BJ, and Charles enters Margaret's tent, Charles steps from behind Hawkeye to look at Williams. A moment later, after the angle changes, Charles steps from behind Hawkeye again.
Continuity mistake: As Ames is pitched the idea of diet and exercise, he has his fork up with a bite of egg on it. When Hawkeye reaches for the fork, it's upside down and clean.
Factual error: When the South Korean Colonel and General are in the Mess Tent with BJ, their rank insignia is wrong. The insignia the Colonel is wearing is for a U.S. Colonel, and the General's insignia would not be three stars in a horizontal line.
Audio problem: While trying to fix the projector, Klinger says, "The bulb is hot!", but his mouth doesn't move.
Follies of the Living - Concerns of the Dead - S10-E10
Continuity mistake: In the Swamp, after another drink, Charles puts a clamp on BJ's hand. As he does, the points are facing Hawkeye. In the wide shot, they're pointing at BJ. Then after Charles passes out, they're pointed at Hawkeye again.
Audio problem: As the Scrounger comes up to Hawkeye and BJ as they walk out after visiting Radar, you hear the horn honk, but the horn button never gets hit.
Character mistake: While talking to Condon, Hawkeye and Trapper relate the story of Dr. Charles Drew, the man responsible for the storage of blood and plasma, and how he died due to not being allowed in a "whites only" hospital after being involved in horrific car accident. The true story is that he was taken to a "poor whites" hospital. Despite being black, he was admitted, and though the doctors worked diligently, his injuries were too severe, and he died. His family sent a warm letter thanking the doctors for their efforts.
Adam's Ribs - S3-E11
Continuity mistake: When Hawkeye throws his food in the mess tent, it lands on the tent screens behind Radar and Klinger. The food is there in the close up shots and in the wide shots it disappears.
The Nurses - S5-E5
Continuity mistake: As The Nurses look at Baker, Walsh is keeping a lookout, then straightens up, partially turns and raises her right arm. A second later, she's back in position, and starts to straighten again.
Continuity mistake: After Klinger throws his ball, his arm stays extended outward. As the shot cuts, looking down the lane towards him, his arm is hanging straight down. Then, after the strike, he raises both arms up. A second later, his left arm is down by his side, his right doing a celebratory motion.
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.
Continuity mistake: After the movie breaks, Hawkeye is giving an over dramatic intro to Margaret. He has his left arm raised, and a second later, both hands are at chest level.
Continuity mistake: While tying a tube around Margaret's arm, Pierce drops the cotton ball with alcohol on it. A moment later, it's in his hand.
Other mistake: It's 1952 when Potter arrives at the 4077. He tells Radar that he joined the army during WWI when he was 15 (he lied about his age). That would mean that Potter was 50 when he arrives. But he said that he'd be retiring in 18 months. Also, in the episode "Point of View" Potter states that this was the first time in 37 years that he missed calling Mildred for their anniversary. That would mean that Potter was 13 when he got married.
Character mistake: The last bet comes to Frank after Mulcahy bets a dollar, and Potter raises fifty cents, making it a dollar fifty. Frank makes it another five dollars, making it six dollars fifty cents. Mulcahy says "Oh dear, it's five fifty to me." He should have said six fifty.
Other mistake: When the Colonel Griswald of the 1st Cavalry goes to leave camp, the Jeep he gets in is marked "4077 MASH" on the bumper instead of 1st Cav.
Revealing mistake: There is a lag between the interior lights going out and the exterior stage lights going on.