Frederick Stafford did not reprise his role as he was filming Alfred Hitchcock's Topaz and was replaced by John Gavin.

[4] The film used an idea of having the hero undergo plastic surgery to fool his enemies, an idea discarded by the film On Her Majesty's Secret Service (1969) that was being filmed at the same time.

The film was shot in Rome and Tunisia.

[6] It was not released in the US despite Gavin's presence in the lead role.

However the film did help Gavin be cast, briefly, as James Bond in Diamonds Are Forever (1971).