Visible crew/equipment: As Hogan and Carter approach the staff car, the crew and film equipment are reflected on the chrome of the lights and radiator.
Visible crew/equipment: As the car with the kidnapped Klink takes off, the Stalag 13 buildings are reflected in the windows, along with the camera equipment and lighting. (00:01:20)
Other mistake: Carter said the plans and note were in the box that was supposed to contain a model of the Hindenburg. However, the box he's building out of has "STUKA" on the side.
Continuity mistake: At the end, Hogan has the note from Nimrod in his right hand. When the shot changes, it's in his left hand.
Answer: It's a solitary cell. Steve McQueen, star of 'The Great Escape' is known as the 'Cooler King'.