USS Greyhound : La Bataille de l'Atlantique

When the Captain refers to "Huff-Duff," he is referring to high-frequency direction-finding. This was a key method of how Allied naval forces detected and tracked German U-Boats: the Kriegsmarine's U-boat fleet maintained a high amount of radio traffic with its shore command and with each other for their Wolfpack tactics against Allied shipping. Huff-Duff allowed Allied naval ships to detect those radio transmissions and determine the location of those transmitting ships to attack them.

One of the German U-boat commanders taunts Greyhound over the radio. This would never have happened in reality. Each Navy ship had a radio signal direction finder and if a U-Boat broke radio silence, triangulation would reveal its exact position.

During the first part of the end credits, some black and white WW2 era clips are shown.

Featured in Half in the Bag: Blumhouse's Dirty Secret (2020)