Goofs

When the Countess spills wine on Klink, he takes his jacket off so she can clean it. When Klink puts on the robe that she gives him, there is a big stain on the front of his trousers. When the Countess kicks Klink out, there is no sign of the stain.

Near the end of the second act (before the denouement), the Countess comes to Klink's quarters, and eventually sends Klink to get some champagne. She then opens the window and gets ready to exit with the plant (the view has shifted to outside the window). However, Schultz comes and interrupts, and he talks to her through the window. Her hands are at her sides, and the plant is not visible. After she tells Schultz to come to her (and he heads for the door), there is a cut from the outside view to the Countess from inside Klink's quarters - but suddenly she is now holding the plant in front of her.

Right at the start of the introduction, Kinchloe hands Hogan a book with a set of negatives in the binding. Hogan pulls the strip out and holds it up to the light to look at it. The view than shifts to show Hogan from the other side, and he is looking down at the strip in his hands. The view than shifts back to the original point (from Hogan's right), and he is looking up at the negatives.

Hitler's mistress Eva Braun is mentioned, but Hitler's relationship with her was a closely guarded secret in part because Hitler wanted to be seen as only for Germany as well as available for German women.

Right at the start of the denouement, Hogan walks into Klink's quarters and turns the lights on (the switch on the wall is a rotary-style switch). There is a noticeable time lag between the click of the switch and the lights coming on, indicating the switch is a prop (or, possibly, the switch is real, just not hooked up), and the lights are controlled from somewhere else. At the time, the bulbs would have been filament-type bulbs, and should have come on immediately as the switch clicked. If the bulbs had been compact fluorescent bulbs (not available then), the delay could have been explained, and even expected.

The scene of Schultz falling into the tunnel is obviously a double. The double's arms and legs are too thin.

In some scenes, a production light is reflecting in Klink's monocle.

Near the start, Carter says that if the Germans find their new tunnel, he will eat his hat. Almost immediately after, Schultz falls into the tunnel and finds LeBeau. There is nothing shown on whether Carter actually tried to eat his hat or not.

Update: After Schultz falls into the tunnel, there is a scene (cut out of the broadcast/syndicated version) where Newkirk pulls Carter's hat off his head, stuffs it into Carter's hands, and says, "Bon appétit." Of course, Carter never does eat his hat, but Newkirk made his point.

In the opening, Hogan looks at a film strip of the details of the new German landmine, and comments on the construction of it. Given the size of each frame, he would never have been able to see any of the important details of the mine with his naked eyes.

Cars and other vehicles often drive over the area where Schultz found the tunnel. There is no way the gang would have built such a flimsy tunnel at that point. As Newkirk indicated, they had almost reached the old tunnel, and it obviously was built to handle the vehicular traffic (or it would have been discovered when the first car drove over it), so they should have built the new tunnel to the same specifications.

When Hogan goes to tell Klink why he should see the Countess again, Hogan and Klink are playing chess. Just before the phone rings (the Countess calling), Klink moves a red pawn two spaces diagonally (as if it were a bishop) - an illegal move, which Hogan allows.

Sergeant Meadowns brings in what he refers to as a 'model' of the new mine. A model most likely would be just a shell of the mine, with nothing inside, which would be useless. He should have referred to it as a 'prototype', or better yet, a 'disabled prototype', which would have indicated that it had all the insides, yet could not be detonated.