The movie was highly realistic except in one respect, and that is something that every sub movie with depth charges gets wrong from Das Boot to U-571.

The sheer number of charges dropped in continuous succession.

Surface ships did not have unlimited charges. The got a fix on where they think the sub is… charge in and as they pass over the suspected sub position, drop a pattern of several charges. Then they circle back, evaluate the effectiveness of the attack, and repeat as necessary.

A good pattern drop would have the sub crew getting several near misses, a couple right on them, then a couple more near misses.

Then there would be a pause in the attack while the Destroyer assesses and repositions for a new attack.

In the movies there is always a continuous series of distant charges getting closer and closer and then suddenly they experience a barrage of 30–40 charges almost nonstop directly on top of them.

The Destroyer would have to be parked, dead stop in the water directly over them for such a continuous non-stop barrage, use up all their DCs, and blow themselves out of the water in the process.