It was directed by Charles Jarrott, produced by Dan Curtis, and written by Ian McLellan Hunter.

[1] Dan Curtis originally engaged Rod Serling to write the script and Jason Robards to star, with filming to take place in London.

Robards, however, was unhappy with the script, and filming in London proved difficult due to a technician's union strike.

[2] With a new script by Ian McLellan Hunter and a new leading man in Jack Palance, Curtis decided to film in Canada, where it would be cheaper to do so than in the US.

Curtis had to pay $200,000 to build a replica of Washington Square in Toronto, and Palance was injured while filming a stunt.