LeBeau removes the file from the middle drawer of the filing cabinet, but returns it to the bottom drawer.
This is another of many appearances throughout this season with Sergeant Schultz wearing a uniform that the costume department incorrectly placed the Luftwaffe eagle and swastika backwards on his jacket. It is evident in a closeup when Schultz is in Klink's office while Hogan complains about the gunfire the night before. The eagle on Schultz's chest should be facing left towards his heart, but is facing away to the right. His backwards swastika is not properly displaying its vertical lines on the upper left and lower right sides, but has them on the upper right and lower left sides.
Metzler states that cables are 6 feet underground. Germany was on the metric system at the time. He should have said 2 meters instead of 6 feet.
The car that the Gestapo uses had the steering wheel on the right; German vehicles have the steering wheel on the left.
When Luisa meets the "Heroes" she is riding a bicycle. As she rides up she leaves tire marks in the dirt. There are multiple tire tracks from previous takes clearly visible.
There are overhead electric wires seen in the background of some of the exterior shots.
The Gestapo wake up Klink in the middle of the night. It's understandable that Hogan is in daytime uniform having been in the car with Hilda but it doesn't explain why Newkirk, LeBeau, and Carter would also be in their daytime uniforms.
At the end, when Klink wants to take his car and go into town, he is looking for his car keys, which Schultz had given to Hogan. Hogan asked Schultz for the keys so he could be with Hilda, and, based on Schultz's response, it is obvious that Hogan had done this more than once (as seen in the introduction). Therefore, Schultz must be the person responsible for the keys to the car. Since Schultz is the person responsible for managing the car keys, Klink would not have needed to check his pockets for the keys (or ask himself where he had put the keys), he should have just asked Schultz for the keys.