Henry Fonda had just turned 31 when filming started. Annabella is supposed to be playing a character of around 20/21, who claims to be 23, but was in fact approaching 30, only one year younger than Fonda.
The first three-strip Technicolor movie shot in Europe; completed in 1936, and bearing a 1936 (MCMXXXVI) copyright statement on the title card, but not released until 1937.
Wings of the Morning is a quotation from Psalm 139, verse 9: "If I take the wings of the morning, and dwell in the uttermost parts of the sea..."
According to the captions, the prologue takes place between 1889 and 1895. The modern story is stated to take place fifty later, which makes the year of the main story 1945.
Filming started with Glenn Tryon as director and Harold D. Schuster as editor; Tryon was fired and Schuster took over in June 1936.