Trivia

The salary of star Charles Bronson was a then exorbitant US $1,500,000. Moreover, this did not include his back-end points percentage profit from the film's box-office grosses and the cost and expenditure for his and wife Jill Ireland's entourage of about a dozen personnel.

For the original UK release, the scene where Charles Bronson builds a makeshift blowpipe from random hotel room accessories, was removed for fear that it might inspire copycat actions. At the same time in British censorship, any movies that showed nunchucks were automatically given "18+" censorship classification rating certificates.

Due to a recent kidnapping of an heiress in the nation of Switzerland, extra security precautions were taken for the picture's production in this country. One of the safety measures implemented was an embargo to all media visiting the set.

Pre-publicity advertisements for this picture in trade paper 'Variety' advertised the fact that this movie was being directed by John Huston. Director Stuart Rosenberg then replaced John Huston as director. Some scenes for the movie were apparently actually directed by Huston but reportedly he left the picture after having creative differences with the picture's producers.

Due to hijack and terrorism threats from the terrorist organization the Baader-Meinhof Group, a permit request to film at the Geneva Airport (aka the Cointrin Airport) was denied, and as such, the intended shoot-out sequence was relocated to the same city's elegant Hotel Beau Rivage.