Stanley Kubrick was the original director, but the film languished in Development Hell until Kubrick died in 1999.
Gigolo Joe was originally conceived by Kubrick as a GI Mecha, but screenwriter Thomas Watson suggested changing him to a male prostitute.
Chris Cunningham was originally the special effects supervisor when the project was being developed in the early '90s. None of his work ended up in the final film.
Part of the reason Kubrick's vision of the film languished in Development Hell for so long was was because he wanted the main character to be played by an actual robot. As of this writing, such robots are still impossible.