This movie was originally intended to be a pilot for an espionage television series, in the style of Callan (1967).
Sir Dirk Bogarde and Ava Gardner appeared in The Angel Wore Red (1960). In the earlier movie, Gardner got first billing, but in this movie, Bogarde got top billing.
The movie was filmed entirely in Austria, particularly Gmunden, Austria.
The main poster had artwork designed by Robert Tanenbaum.
The name of the spy organization was the "Western Intelligence Liaison". MI5 is also referenced in the movie.