Top Hat, White Tie and Bomb Sights - S1-E10
Revealing mistake: When General Burkhalter has entered the camp and is stopped at the gate, the camera cuts to Hogan and the guys. Above the barracks, you can see the Desilu water tower. (00:15:30)
Color the Luftwaffe Red - S4-E8
Revealing mistake: When the truck with Hogan and company pulls up to the Luftwaffe HQ, the camera pans to the right to look at Klink getting out of the side car. When the camera cuts back to Hogan and company, they shake as if the truck just stopped, but it can be seen that the truck was stationary.
Revealing mistake: When Schultz is on the way out after giving the guys the news about the inspections and roll calls, you can plainly see that the background behind him is a matte painting. This is easy to spot because the building in the distance is lighter in color, and there are ripples in the fabric used.
I Look Better in Basic Black - S1-E28
Revealing mistake: When Hogan, Newkirk and Lebeau are dressed as the three women captured by the Gestapo, demand the truck be stopped, the wide shot shows that the truck is already stopped, and shaken to simulate it stopping.
Revealing mistake: When the guys are by the half-track keeping Shultz busy, if you look just above and to the left of Shultz's head, you see some tall fencing at the top of the hill in the distance. From the set up, if appears to be a baseball field outside of the studio property.
Revealing mistake: When the men are in the yard during their exercise period playing football, there is a wide shot of the yard. The half-track is to the left of the screen with Shultz next to it. If you look above the barracks, the Desilu water tower and a large metal building, possibly a studio building, can be seen.
How to Cook a German Goose by Radar - S1-E24
Revealing mistake: Toward the end of the episode, a guard is watching Helga posing in a one piece bikini for Lebeau. As you look past him, you see only blue screen, no view of the surrounding property. Same when Hogan climbs up, you don't see the tops of buildings; you can tell it's on a soundstage.
How to Cook a German Goose by Radar - S1-E24
Revealing mistake: After Hogan and the boys decide to get rid of Tillman, they "accidentally" set fire to the trash can on the Kommandant's porch. To that end they load up a bunch of trash that's been soaked in gas. Then Hogan tosses a lit match in it. The fire starts at the bottom, but all of gas soaked stuff, and the match, were at the top.
I Look Better in Basic Black - S1-E28
Revealing mistake: A very long fuse is laid down then lit by the boys to distract the guards. While it is burning, watch the fuse in the dirt - it is actually being pulled from offscreen to the right of the shot.
How to Cook a German Goose by Radar - S1-E24
Revealing mistake: When the boys set the trash can on fire in front of Klink's office, there is a problem with the trash. While the rest of the waste paper burns down there is one piece hanging over the top edge that doesn't burn, even being in the midst of the flames on that side.
That's No Lady, That's My Spy - S6-E17
Revealing mistake: When the men are in ranks for roll call, it's snowing heavily. Given the pitch of the barracks' roofs, there shouldn't be any snow sticking. Therefore, if looked at closely, it can be seen that the "snow" on the roofs is painted in place.
Will the Blue Baron Strike Again? - S4-E12
Revealing mistake: When Hogan, Newkirk, and Carter are at the Blue Baron's secret airfield, Hogan opens the barrel and stuffs in a rag and lights it so it will be a flare for the Allied bombers. The flight line and the planes on it are an obvious cutout. The fire couldn't have spread to the surrounding ground like it was shown. Also, when the bombs were going off on the airfield, you can see that the explosions are very small charges behind the cut outs.
Revealing mistake: The bunk that is the entrance to the tunnels appears to be moving upward about a split second before Newkirk taps the hidden key to activate it.
Revealing mistake: Whenever there is a shot of the outside of the barracks, where it can be seen that it is outside on the studio lot, look at the "snow" on the roofs. Most of the time, it appears to be just paint in the shape of snowdrifts.
Revealing mistake: As the building is being prepared for the upcoming event, and men are going in and out, as Shultz goes to report to Klink, look past him and the roof behind him. You can see the studio water tower in the distance.
Revealing mistake: During the attack with crossbow, look closely at the arrow in the door. You hear the sound of the arrow hitting the door, then see the (now skewered) hat shaking on the arrow. If viewed closely, you see a black thread pulling on the arrow. Also, the arrow is almost straight before the break, then it is down at an angle when Shultz is called in.
Revealing mistake: Every time they go to destroy a truck convoy, you can see that it is a miniature set with model trucks blown up, and it is a re-used shot every time. Same goes for the trains that get blown up.
Answer: It's a comedy, not a documentary.
stiiggy
Perhaps it was counterfeit. There are numerous episodes where they deal in counterfeit monies.