At one point when Deborah Kerr's character wanders around the house at night with only a candelabra for illumination, you might think you see something in the corner of your eye. You do. It's the clapperboard which had briefly wandered into shot. Jack Clayton decided to keep it in because he liked the idea of something almost subliminal being present to add to the air of unease.
Two of Michael Redgrave's children eventually appeared in different adaptations of the same story. Lynn Redgrave appeared in the 1974 version of The Turn of the Screw, and Corin Redgrave appeared in the 2009 version.
Jack Clayton didn't want the children to be exposed to the darker themes of the story, so they never saw the screenplay in its entirety. The children were given their pages the day before they were to be filmed.
Jack Clayton was dismayed to learn that 20th Century Fox insisted on making the film in CinemaScope. His cinematographer Freddie Francis set about making that less of a problem by framing the wide horizontal frame with lots of vertical lines to break it up. Conversely, he also used the wide space to emphasize shadowy spaces and using the emptiness towards an unsettling effect. To that end, he would often place characters at opposite ends of the frame.
The film opens with a creepy song written by Paul Dehn and Georges Auric sung over a black screen for about 45 seconds before the 20th Century Fox logo appears. In some cinemas, the projectionists assumed this was a mistake on the print and edited the film so it began with the appearance of the Fox logo.