The bunk bed that conceals the ladder that goes down into the tunnel is shown as being in a corner. Yet when Kinchloe comes up the ladder the camera shot is from an angle that would be impossible due to a wall being in the way.
When LeBeau puts the thermometer in the spout of the coffee pot on the stove, the 'steam' from the spout is actually settling downward - not upward. And the 'steam' is hanging in the spout itself, again, not rising upward. This indicates the 'steam' is actually something else - probably carbon dioxide gas from a piece of 'dry ice' in the coffee pot (or spout).
When Schultz leaves Hogan's room after checking on Newkirk for the second time, Schultz closes the door. When the door closes, the record player (playing the sounds of snoring) apparently skips (the sound of the needle dragging across the tracks of the record is heard, even though the arm lifted up - it did not drag on the record). In actuality, the record player had detected that the arm and needle had merely reached the end of the snoring record, and recycled to play the next record.
In the intro segment, when Schultz turns to LeBeau and says, "Apfel Strudel!", the camera zooms in on Schultz. When it zooms in, a shadow from the camera moves up Schultz's right arm.
In some scenes, there are reflections in Klink's monocle from the production lights.
Nothing is mentioned as to what happened to Myra. She was down in the tunnel and saw Hogan's entire operation. If Hogan left her at Gestapo Headquarters, she would have told them when they got back of the operation. If something else happened to her, it was not mentioned. Update: When they freed Newkirk, Hogan said to release Gunther and Franz and hand Myra to them for transport back to England.
Colonel Hogan has word sent to the Gestapo that they will meet them in the woods at 2400 hours. An army officer should know that 12 midnight is always referred to as zero hundred hours.
Hogan and Kinchloe both refer to 510 as being the emergency 'wavelength' - when dealing with communications, electromagnetic wave communication channels are based on frequency, not wavelength. Both would have used 'frequency' to describe the emergency channel.
When Hogan takes the thermometer from LeBeau, he flinches, as if the thermometer were too hot to hold - yet LeBeau had no problem holding it and handing it to Hogan.