Revealing mistake: During the main part of the plot, the guys are putting dynamite on each truck in the convoy as they fuel up at Stalag 13. It is supposed to be dark, (hence the reason the boys wear black) but there are shadows as if it were day. It's impossible for the driver in the following truck and the guard in The Tower to miss seeing the boys as they go back and forth to plant charges.
Continuity mistake: When the man and woman from the underground meet Hogan at the Hoffbrau, they're taking off their outer coats. The man takes off a dark brown coat and drops it. Hogan picks it up, hands it to the guy who hangs it up. The man removes his dark brown overcoat revealing a tan coat. The next shot, he"s taking off the dark brown coat again, hangs it up and goes for beer.
Other mistake: When the Heroes are outside talking, the camera focuses on Col. Hogan. Over his right shoulder you can see a hill with a baseball field's home plate fencing on top.
Continuity mistake: In Klink's quarters, As Schultz and Klink talk, Klink asks a question and takes a bite of steak, and the fork is still up. After the angle change, the fork is suddenly missing.
Other mistake: As Schultz goes to stick a pin in the map, he supposedly hits his finger. But if you look closely, he actually stuck it in the map at the very tip of his finger. This is clear because he didn't move the pin at all.
Other mistake: As Schultz tries to find Flensheim on the wall map, what he's checking isn't a road map, but a city plan with a harbor on it.
Answer: It's a comedy, not a documentary.
stiiggy
Perhaps it was counterfeit. There are numerous episodes where they deal in counterfeit monies.