Although the film was supposed to have been shot in many locations, the scenes in Greece and New York's port (at the end of the movie), were in fact filmed in Naples, Italy. Names and banners were created to make it look like the locations they were supposed to be, but they were riddled with typographical errors; in addition, the real port of Piraeus doesn't look anything like the one depicted in the film.
In Sept. 1957, Columbia Pictures distributed this film under the title "Pickup Alley" on a double bill with The Brothers Rico (1957) starring Richard Conte.
The story was based on the files of the International Criminal Police Commission.
Exteriors for the film were shot in England, Italy and Portugal, but the majority of the interiors were shot on a sound stage in London, England.
Co-producer Albert R. Broccoli is best known as a producer for the bulk of the James Bond franchise. Cinematographer Ted Moore would later go on to be the Directory of Photography for 7 of the first 9 films in the series.