Visible crew/equipment: As Klink's car pulls up, and Klink comes around the front of it, the shadow of the camera is visible.
Nights in Shining Armor - S3-E8
Other mistake: When Hogan shoots the vest, it stays still for a couple of seconds then swings in a way that is not normal.
What Time Does the Balloon Go Up? - S3-E24
Plot hole: Hogan has the men fly kites to get wind data and build a hot air balloon for a man to escape in. In reality, kites and hot air balloons are pretty much mutually exclusive - if there's enough wind to fly kites, one can't launch a hot air balloon, and vice versa.
Factual error: Towards the end of the episode, Burkhalter gets a call from a General Seidenbaum. Anybody with such a "Jewish" name would have been weeded out of the officer corps by the Nazis. In fact, anyone of that name would have had great trouble even getting his Ariernachweis (proof or aryan ancestry), and without carrying a copy with him he could not have opened a charge account at the local bakery. Most people with such names (those who managed to pass the Nazi board of racial review) had them changed to more "German" ones like Müller or Schmidt to escape the constant bullying. A little bit of background on "jewish" names: At some time during the medieval period, Jews in the German Reich who traditionally didn't use last names were forced to have them. Many selected names like Gruenbaum, Cornfield, etc. Which over time were perceived as "typical Jewish" names, even though many bearers weren't even of Jewish faith any more.
Drums Along the Dusseldorf - S3-E30
Factual error: All through this episode, characters keep referring to the river the bridge *du jour* spans as "The Düsseldorf" or "Düsseldorf river." The city of Düsseldorf is situated on the river Rhine - there is no "Düsseldorf river." It's a well known fact that the producers were hardly geography whizzes, but not knowing the Rhine is bad even by their standards. Curiously enough, there kinda is a "Düsseldorf river" called the Düssel, and it meets the Rhine there. The Düssel however is a small streamlet that a well-trained man could probably jump over - so the mistake is still a valid one.
Other mistake: Towards the end, the shot of the plane landing is a recycled shot. Even though Klink waved the flashlight, an unidentified person can be seen in the shot waving a signal light in the midst of the field. Klink was by his car.
Continuity mistake: In Hogan's quarters, as he and Critendon are talking, his arms are by his sides, and suddenly crossed. As Hogan goes to get his hat off Critendon's sword, his right hand is shown, then after the angle changes, his left hand draws back with the hat, and his right comes up to grab it.
Nights in Shining Armor - S3-E8
Other mistake: In Hogan's quarters, after Hogan reveals the two Aces up Newkirk's sleeve, Newkirk goes to brush his hair. As his hand goes up, you can see the cards in his hand.
An Evening of Generals - S3-E13
Revealing mistake: The silver rack with bowls starts moving a second before the rocking explosion.
An Evening of Generals - S3-E13
Continuity mistake: As Klink is listening to Burkhalter, he is gesturing with a blue pencil. A second later, it's yellow.
An Evening of Generals - S3-E13
Continuity mistake: As Klink is listening to Burkhalter, his right hand is on the desk. A second later, it's at the top of his chest with his left, holding a pencil.
Revealing mistake: After the cell door blows, you can see the fuse of the stick of "dynamite" Newkirk placed still burning on the ground. Since the dynamite would blow when the fuse is burnt up, that literally can't happen. (00:22:40)
Sergeant Schultz Meets Mata Hari - S3-E4
Audio problem: You hear Carter ask, "Hey, what are you doing with my mattress?" as the Gestapo searches the barracks, but his mouth doesn't move.
Drums Along the Dusseldorf - S3-E30
Continuity mistake: At the end, when Hogan and Schultz are admiring the Indian headband sent by Carter, Klink comes walking out behind them. As he stands in the door, you see Klink fold his hands in front of his waist as Hogan is talking. After Klink starts to talk, the camera cuts to a close up of him and he suddenly has his riding crop under his arm.
Everybody Loves a Snowman - S3-E14
Revealing mistake: When Hochstetter goes to open the snowman, you can see the plug is a poorly disguised piece of wood, as well as the piece of metal around the opening in the snowman.
Factual error: The guard delivering the Russian captive in the tunnel at the start of the show has a paratrooper M1 carbine with a bayonet lug. Bayonet lugs were not attached to M1 carbines until after the war.
Funny Thing Happened on the Way to London - S3-E5
Revealing mistake: When the staff car enters the camp, you see a set of tire tracks leading up to, and stopping at, Klink's position. When the car comes in, it precisely follows the tracks, suggesting previous takes.
How to Win Friends and Influence Nazis - S3-E7
Continuity mistake: In the long shot of the hotel room, the boys are lulling Schultz to get him to sleep. In the long shot, his right hand is holding the rifle. In the close up, it's barely draped over the rifle.
LeBeau and the Little Old Lady - S3-E25
Continuity mistake: When Newkirk and Carter are playing Gin, Newkirk puts a card on his forehead so Carter can't get it. When he puts it on his head, it's about a quarter inch below his hairline. In the close up, the card is now at the hairline. In the wide shot, the card is again about a quarter inch lower.
Answer: It's a solitary cell. Steve McQueen, star of 'The Great Escape' is known as the 'Cooler King'.