Revealing mistake: After the cell door blows, you can see the fuse of the stick of "dynamite" Newkirk placed still burning on the ground. Since the dynamite would blow when the fuse is burnt up, that literally can't happen. (00:22:40)
Visible crew/equipment: As Klink's car pulls up, and Klink comes around the front of it, the shadow of the camera is visible.
Answer: It's a solitary cell. Steve McQueen, star of 'The Great Escape' is known as the 'Cooler King'.