This movie's closing epilogue states: "Twentieth Century-Fox wishes to thank the Department of Defense and the United States Navy for their assistance in the production of this motion picture."
This picture marks the feature film movie debuts for David Hedison (as Al Hedison); Dan Tana and Ted Perritt, the latter of whom was a former messenger boy at the 20th century-Fox studio, playing a messenger.
Though set in the South Atlantic Ocean of World War II, this movie's ocean scenes were filmed in the Pacific Ocean.
To add further confusion to the ship's identity, although called the Haynes in the movie, the ship's hull number is shown as DE-181, which was the USS Straub, a Cannon class destroyer escort.
Two endings were shot: In one, both commanders die; in the other, a third vessel rescues them. The final ending was determined by preview results. The 'USS Haynes' was portrayed by the 'USS Whitehurst', captained by Walter R. Smith, who received a "technical advisor" credit and can be seen portraying the ship's chief engineer. Eva Novak can be seen in a photo as the wife of Von Stolberg.
Eva Novak:
As the wife of the German submarine commander, Von Stolberg (Curd Jürgens). Though Novak neither appears in the live-action of the movie itself nor is listed in this movie's cast credits, Novak is seen in a photograph appearing as Mrs Stolberg.