Attention to detail was particularly important to the producers, so all of the naval procedures depicted in this movie are completely accurate. The scene where Harwood meets with his Captains on board the Ajax, however, was a fictitious one, created in order to explain the situation to the audience.
The U.S.S. Salem was a World War II-vintage Des Moines-class heavy cruiser, armed with nine eight-inch guns. In this movie, we can also see the three-inch AA guns installed to combat Kamikaze attacks.
H.M.S. Cumberland played herself. However, she had been withdrawn from front line service and was being used as a gunnery trials ship, with various prototype turrets installed from time to time, so that they could be evaluated. When she appears towards the end of the movie, it is obvious that her forward turrets (A and B) have been removed, and a small prototype turret installed in the X (aft) position. H.M.S. Cumberland was finally scrapped two years after the shooting of this movie.
The midshipmen's quarters were empty because Captain Langsdorff had promoted all of his midshipmen to ensigns in order to make room for his prisoners.
The photo of the Admiral Graf Spee in the Captain's cabin was taken at the Fleet Review in Spithead in 1937. The two ships in the background are H.M.S. Hood and H.M.S. Resolution.