Das Boot (1981)

Continuity mistake: At the end of the first attack by the destroyer - where she misses the U-boat and throws her bombs further away - the boatswain makes 22, then 23 strokes on the slate of the Control Centre,thus counting the number of depth charges used against the boat.A few seconds later, in a shot from another angle, with the slate in full view, we see only 22 strokes. (01:03:30)