The first use of computer digitized images as part of a feature film (not merely monitor graphics) was the Gunslinger's point of view in Westworld. After the process was finally developed enough to produce satisfactory results, it took a mere eight hours to produce each ten seconds of footage for the Gunslinger's pixelated POV.
Yul Brynner was suffering from financial difficulties in the early 1970s and in desperate need of money. With no other movie work on offer to him at the time, he reluctantly agreed to play his role for a knockdown $75,000, which comes out to $485,648.65 in 2022.
Both Richard Benjamin and James Brolin were cast less than 48 hours before filming was due to begin.
The robot that Yul Brynner portrays is an homage/spoof of his character Chris from Sete Homens e um Destino (1960) and wears the same costume.
There were several minor injures during filming. During a shootout scene a piece of wadding from a blank cartridge struck Yul Brynner in the eye, scratching his cornea and leaving him unable to wear his light reflecting contacts without his injured eye turning red and tearing up, so shooting had to be maneuvered to allow time for his eye to heal. And during the scene where James Brolin's character was bitten by a rattlesnake, while the milked rattler was attached to Brolin's arm, he was bitten by the teeth on the snakes lower jaw, despite wearing padding on his arm made of leather and cotton.