The password that Hardt is to use for his contact is the opening line of Heine's poem Die Lorelei, in which a beautiful woman, who lures sailors on the rocks, is used as a symbol of homesickness. When his crew joke about him spouting love poetry to a woman in the dark, they miss half of the point.
St Magnus (the name of the steamer sailing from Longhope for St Romness and Thurso during the closing stages of the film) is the Patron Saint of Orkney. There have been several ships in that area with the name St Magnus.
Local information from Orkney reports that it may have been the St Ola 1 that appeared in this film, apparently sunk by U29. In real life the St Ola 1 served the route Thurso to Stromness between 1892 and 1951, with a few cancellations in rough weather, for the safety and comfort of passengers.
This film was included in the first syndicated television presentation of a package of major studio feature films on USA television; it premiered in New York City Sunday 29 August 1948 on WPIX (Channel 11), followed by Baltimore Thursday 9 September 1948 on WMAR (Channel 2), by Philadelphia Friday 17 September 1948 on WFIL (Channel 6), by Chicago Monday 4 October 1948 on WGN (Channel 9), by Los Angeles Sunday 17 October 1948 on KTLA (Channel 5), and by Atlanta Wednesday 24 November 1948 on WSB (Channel 8). The package consisted of 24 Alexander Korda productions originally released theatrically between 1933 and 1942.