Stupidity: No U-boat commander is going to "finish off" a ship that is dead in the water and is on fire from stem to stern. He exposes his boat and his men to mortal peril by surfacing, brightly lit by a full moon and the fires burning on the sinking ship, making them a sitting duck for the destroyers that might well be still in the area. He also wastes a precious torpedo for absolutely no net gain.
Das Boot (1981)
1 stupidity
Directed by: Wolfgang Petersen
Starring: Jurgen Prochnow, Herbert Gronemeyer, Hubertus Bengsch, Klaus Wennemann
Revealing mistake: In one scene just before the attack on a big Hunter the young captain (Jürgen Prochnow) is sitting with his charts. Beside him he has got a glass of beer standing. The sub lurches heavily right and left in the hard weather, but the surface of the liquid stays the same.
Captain: April fool. Practice makes perfect.
Question: What's the music the German band are playing at the end when U96 returns to port?
Answer: It's the 'Erzherzog Albrecht Marsch', composed 1887.