Revealing mistake: In this scene we see Claudette Colbert and her husband talking. In the background it's obvious the ocean scene is a stage prop, the waves in the sea don't move at all.
Revealing mistake: When there's a cave-in in the tunnel the POWs are building, you can hear, as the POW is tunnelling out of the cave-in, his trowel hitting the glass that separates him from the camera and crew.