The scene set in the church where Laura lights a candle for Christine was mostly improvised. Originally intended to show the gulf between John's and Laura's mental states-John's denial and Laura's inability to let go-the script included two pages of dialogue to illustrate John's unease at Laura's marked display of grief. After a break in filming to allow the crew to set up the equipment, Donald Sutherland returned to the set and commented that he did not like the church, to which Julie Christie retorted that he was being "silly," and the church was "beautiful." Nicolas Roeg felt that the exchange was more true to life in terms of what the characters would actually say to each other, and that the scripted version was "overwritten," so opted to ditch the scripted dialogue and included the real-life exchange instead.
Renato Scarpa, who plays Inspector Longhi, didn't speak any English: he just read the lines he'd been given without knowing what they meant. This added to the sinister quality of his character.
Shooting the drowning sequence was particularly problematic: Sharon Williams, who played Christine, became hysterical when submersed in the pond, despite the rehearsals at the swimming pool going well. A farmer on the neighbouring land volunteered his daughter who was an accomplished swimmer, but who refused to be submersed when it came to filming. In the end, the scene was filmed in a water tank using three girls.
Donald Sutherland and Julie Christie met for the first time on the set of this film. The first scene they had to shoot was the sex scene, as Nicolas Roeg wanted to "get it out of the way" and then move on to the "bone" of the matter. Christie was terrified.
When he appeared on Actors Studio (1994), Donald Sutherland recounted the story of how the (In)famous sex scene was actually shot and that it was anything but a sexy or erotic experience for those involved. He and Julie Christie were on the set at 7 a.m. in dressing gowns, waiting downstairs while the room was prepared and both had a glass of champagne to calm their nerves. Inside the room was Nicolas Roeg and cinematographer Anthony B. Richmond, each operating their own Mitchell 35mm camera. Sutherland and Chiststie disrobed and got onto the bed and Roeg and Richmond began filming. The huge Mitchell cameras were unblimped (unsilenced) so the noise from the two cameras was amplified hugely. At the same time, Roeg began shouting directions (over the noise of the cameras)to the actors such as "Lick her nipples" "Put your hand between her legs" "Get on top" etc.The shoot lasted until well into the afternoon before Roeg was satisfied and wrapped. However, the cameraman on the film, Anthony Richmond) has related a very different account of the shooting of the scene, saying that it was wrapped up quickly in no more than an hour and a half (see below).