Neil Jordan wanted his longtime collaborator, composer Elliot Goldenthal to do the film, but Goldenthal was committed to score Titus for his companion, Julie Taymor. John Barry was considered, and he wrote a demo theme for the film, which ended up on his 2001 solo album "Eternal Echoes," but Jordan eventually settled on Michael Nyman.
The film that Maurice and Sarah see is 21 Days Together. Graham Greene, the author of novel on which The End of the Affair is based, co-wrote the script for 21 Days, although the name of the film they see in the novel is never mentioned.