Trivia

This movie was released in the U.S. on a double-bill with Torture Garden (1967).

Despite having being billed third and above the title in the main credits, Sir Michael Redgrave only has three scenes.

Third of three consecutive back-to-back-to-back spy movies by Writer and Director Val Guest. The first was Where the Spies Are (1965) and the second was Casino Royale (1967) which Guest co-directed. He co-wrote all three as well.

Jan Werich was dubbed.

Agent Philip Scott's (Stephen Boyd's) codename was "Mercury".