In the novel, Christine's diary is in the form of a journal / notebook, whereas in the film it is a camera for obvious visual reasons.
Nicole Kidman studied amnesiacs in preparation for this film, including watching a documentary on Clive Wearing.
This was the last feature film to use Fuji 35mm film stock. Production of this film stock ceased at this time.
Director Rowan Joffe had originally been given the manuscript of the film by TV producer Liza Marshall, with no cover. Initially reading and thinking it was a memoir/straight drama in novel form, he was shocked to discover it was a thriller as he read more.