When Klink delivers his speech, he talks about himself growing up in Dusseldorf, but in Hogan's Double Life (1971), he reveals that he grew up in Leipzig. Even went to school there.
The truck has the steering wheel on the right; normally, German trucks have the steering wheel on the left.
In some of the scenes in Klink's office there are heavy shadows on the back wall. From the angle, the production lights are shining from the upper right above the camera.
After the rocket takes off, Major Hauser is seen on the rocket platform in tattered uniform. If he were really that close to the rocket when it took off, he would have been burned to a crisp by the exhaust.
After Carter tells Hogan that the Germans have brought something big into the camp, Hogan uses the periscope to get a better view of a rocket and says, "It's really big...even bigger than a breadbox." However, the phrase "larger than a bread box," was not coined until well after World War II in 1953 when Steve Allen first asked "Is it larger than a breadbox?" on June Havoc (1953).
There is a reflection in Klink's monocle from the production lighting in some scenes.
The guards release the dogs to find the missing prisoner; however, LeBeau spends a lot of time with the commandos outside the camp but no guards turn up. Wouldn't it be logical that the German guards would follow their dogs?
When LeBeau is trying to contact 'Red Riding Hood' on the walkie-talkie, he works the 'talk' (transmit) button, but does not hold it in when he actually talks. Therefore, no signal is ever sent. Even when he is talking to 'Goldilocks', he does not hold the button down.
When LeBeau (Robert Clary) is taking measurements of Dr. Schneider in the woods, he calls out the last number without looking at the tape measure.
When Hogan goes under the cover to meet with Dr. Schneider and plant the bomb (Schneider tells him where to put it), it is established that they have not met. However, since Hogan and the gang made the uniforms and all the other equipment for Dr. Schneider and the other commandos, it would have made more sense for the bomb to have been hidden in Dr. Schneider's overcoat, rather than risk Hogan going under the cover.