Filmed near Victoria, British Columbia, from July to September, 1942.
Alexander Knox, credited eighth as the German captain, also provides the uncredited voice of the off-screen Chaplain of the British naval vessel, as well as that of the off-screen closing narrator.
Behind-the-scenes footage made during location filming in Canada is included in the CBC-TV documentary Canada's War in Color (2005).
The ship used in the film was HMCS Prince David (F89). Filming took place from 24 July to 27 July 1942. HMCS Prince David and her sister ships HMCS Prince Henry and HMCS Prince Robert were former CN Steamships. They were built as small, fast luxury liners ordered in 1929 to serve on Canada's West Coast and converted to Armed Merchant Cruisers in 1940.
At the time of the filming the Prince ships were the largest in the RCN.
Bristol Bolingbroke (Canadian versions of the Blenheim) light bombers and Westland Lysander liaison aircraft were painted up with German Balkankreuz markings to stand in for unavailable Luftwaffe types.