This film has many tangential connections to Casablanca (1942) besides its plot line of anti-Nazi intrigue. It features Paul Henreid, Sydney Greenstreet and Peter Lorre, who all appeared in "Casablanca." Behind the scenes, the film features music by Max Steiner and cinematography by Arthur Edeson, who both worked on "Casablanca." Like "Casablanca," it was produced by Warner Bros. It also features Hedy Lamarr, who was originally considered for the role of "Ilsa," which was eventually played by Ingrid Bergman. Lamar had also previously appeared in Casbah (1938), which had a plot line similar to "Casablanca." In "Casablanca" and this film, the city of Lisbon is referenced as the port of departure for the United States and other points in the non-Axis world. Moreover, Lisbon is the main setting for this film.
Don Siegel was to have made his directorial debut with this film, but after a spat with Warner Bros. chief Jack L. Warner, he was demoted to assistant director and Jean Negulesco was assigned as director.
This is the eighth of nine films in which Sydney Greenstreet and Peter Lorre both appear, all released by Warner Bros. from 1941 to 1946.
The travel agent, Thos. Course & Sons, is likely a reference to the British travel firm, Thomas Cook and Son. Cook was a British entrepreneur who developed conducted tours in the UK and overseas. His firm had branches in many foreign countries.
A song, "Orchard Moon," with music by Max Steiner and lyrics by Al Stillman, was published in connection with the picture.