Max von Sydow, who plays Joanna Miles' father in the film, was in reality only eleven years older than her.
The starring role of Carson was originally supposed to go to Chia-Hui Liu aka Gordon Liu. In the end the lead role was cast with movie star Yul Brynner.
The picture's gigantic subway set spanned across two sound-stages at the Warner Bros. studios in Burbank, California as reported in an article published in the 29th August 1974 issue of 'The Los Angeles Herald-Examiner' newspaper. The piece stated that it was believed to be to that time possibly the largest interior movie set in the history of filmmaking in Hollywood.
The picture featured no on location filming and was entirely shot on the back lot at the Warner Bros. Burbank studios and at the M-G-M studios in Culver City, California.
The time-frame and place setting that the film takes place in is New York City in a futuristic apocalyptic post-virus-pandemic holocaust civilization of 2012.