An original member of the real-life mini-sub operations, Commander Donald Fraser, who had been a lieutenant at the time of the mission, acted as a consultant and advisor to the film production.
In this movie, the name of the vessel that carried the manned human torpedo chariots was called "Ingebord" but in the real-life it was really named "Arthur".
Original military equipment from World War II was accessed and used for the making of this movie.
The attack by midget submarines did considerable damage, and actually put the Tirpitz out of action. The Tirpitz was later sunk using gigantic 6 ton bombs by R.A.F. Sqn. 617.
The central event of Above us the Waves is the x-craft attack on the battleship Tirpitz. The Captain of x-craft 5, was in reality Henty Henty-Creer. Before the second world war Henty Creer was a film camera man and worked on 49th Parallel, The Thief of Bagdad and The Four Feathers.
The code-name of the real life World War II mission that this film was based on was Operation Source. This operation utilized the Royal Navy's midget X class submarines.
The watch on Commander Fraser's wrist is the famous Jaeger-LeCoultre Reverso, a watch with a case that can be turned around so that the front faces downwards, thus protecting the glass from hard knocks. This robust watch is nowadays considered as an ultra-luxury item.
This movie features a scene where there is an underwater man-to-man fight between Nazi German and British frogmen in an anti-submarine net but in the real-life mini-sub attack on the Tirpitz, this fight did not occur.
This movie is based on both the real-life Chariot human torpedo attacks on the German battleship Tirpitz during the Second World War as well as Operation Source, which was a series of attacks by X-class midget submarines on Nazi German warships, the Tirpitz, Scharnhorst and Lutzow, in Northern Norway during World War II.
When the film was made Queen Elizabeth II was on the throne, but throughout the war it was her father, King George VI, who was the monarch. Whether by design or chance most of the cast in the film have historically accurate cap badges, which is to say they include a King's crown. The notable exception is John Mills, whose cap badge has a Queen's crown.