The huge escalator linking this World with the Other, called "Operation Ethel" by the firm of engineers who constructed her under the aegis of the London Passenger Transport Board, took three months to make, and cost three thousand pounds sterling (in 1946). "Ethel" had one hundred six steps, each twenty feet wide, and was driven by a twelve horsepower engine. The full shot was completed by hanging miniatures.
The first scene shot was David Niven washing up on the beach. Originally planned to fade in from black, Michael Powell decided on the spot that the effect would be too cheesy. When Jack Cardiff told him to look through the camera, Cardiff then deliberately breathed onto the lens, which fogged the glass for a few seconds until it evaporated. Powell loved the idea and had him use it for the shot.
According to Ben Mankiewicz of Turner Classic Movies, this movie's production was delayed nine months due to the scarcity of Technicolor film and equipment at the time. That makes Conductor 71's remark upon leaving black-and-white heaven somewhat of an inside joke.
The inspiration for Peter's medical condition came from the semi-autobiographical novel "A Journey Round My Skull" by Hungarian novelist Frigyes Karinthy. More precise medical detail came from Emeric Pressburger's research in the British Library and consultations with Michael Powell's brother-in-law Dr. Joe Reidy, who was a plastic surgeon in London.
It was during a visit to Hollywood in 1945 that director Michael Powell decided to cast the then-unknown Kim Hunter as June, the American servicewoman, largely upon the recommendation of Sir Alfred Hitchcock, who had done a series of screen tests of actors and actresses auditioning for parts in his upcoming production, Notorious (1946). The trouble was that in these screen tests Hunter was not seen but, was heard off-camera, feeding lines and cues to the actors Hitchcock was screen-testing. But Hitchcock assured Powell that he would arrange a "face-to-face" with Hunter and her agent, so that he could see for himself whether she fit the requirements of the all-American girl Powell had envisioned opposite David Niven. And upon first encountering Hunter, Powell agreed with Hitchcock that she, indeed, was a perfect choice for the role.