Patrick Macnee readily confessed that his famous portrayal of John Steed in The Avengers (1961) was, in many respects, based upon Sir Ralph Richardson's performance as the louche hat-wearing, umbrella-wielding Major Charles Hammond in this film.
The ocean liner, over which Tony McVane (Laurence Olivier) flies, is the French ship S.S. Normandie. She caught fire and capsized in New York City harbor on February 9, 1942 and was scrapped in October 1946.
With the overtones of war approaching, when the British released the film (1939 before the start of WW2) in the United States- the title was changed to 'Clouds over Europe." The opening of the film was much more sinister as it started off with pictures of scenes of London and an announcer advising what a difficult time the Empire was having with safety and trade as clouds of war appeared near. The change was a direct way of England trying to gain support from the neutral United States.
The test plane was an Airspeed AS 6 Envoy (not the AS 10 Oxford, note the much larger rectangular windows behind the distinctive cockpit windshield). First flown in 1934, it served primarily as a transport and training aircraft during World War II. Several variants were made, the primary difference being the engines used. One was outfitted for use by the Royal Family. Production ceased in 1939 with only fifty-two being made.
The destroyer sent to intercept the S.S. Viking is the H.M.S. Echo (H23). This was one of nine E-class destroyers of the Royal Navy. She was launched in 1934. During World War II, she sank a U-boat in 1943, and was transferred to the Greek Navy in 1944.