When the German POWs reach the sea and look out to see from the caves, the filmed footage of the U-boat surfacing appears to jump.
In the opening minutes when the German POWs are preparing to riot, they sing "Erika". However, during the chorus a kettle drum is plainly heard. There is no kettle drum present. Furthermore, when Captain Schleutter sings along, his lips aren't synchronized with the song. Apparently, they had a men's chorus sing "Erika" in a recording studio and then dubbed it in later.
Although it is raining heavily in many scenes, the ground remains mostly dry. There is no dirt visible on the character's clothes after they fought each other on expectedly wet sand and grass.
The Jeep used is a civilian CJ 3B model, first introduced in 1953.