The scene in which Carol encounters the disemboweled dogs in the clinic became quite controversial because of the startlingly realistic (and graphic) appearance of the fake prop dogs. Director Lucio Fulci was nearly sent to prison because it was believed that the dogs were real and Fulci had allowed animal cruelty on the film. However crew members were able to testify in court that the "dogs" were indeed fake and no animals had ever been harmed. Special effects artist Carlo Rambaldi even presented the dog props in court to convince the jury. This was the first time that an effects artist had to testify in court that their work was fake.
The house outside which the police car pulls up and which is supposed to contain Carol's flat is 39 Belgrave Square, SW1. In real life it is occupied by the Italian Cultural Institute in London.
A Francis Bacon painting of a screaming figure sitting in a chair hangs in Carol's living room. The painting is alluded to in Carol's surreal nightmare when she encounters several horrific, garish figures sitting in chairs with faces frozen in a scream.
The striking painting of the swan above Carol's bed is a representation of Salvador Dali's set for Leonide Massine's "Bacchanale". The dancers emerged from the hole in the swan's chest.
Leo Genn plays a lawyer in the film. Before becoming an actor, Genn was a practicing barrister, and was a prosecutor in the Belsen war crimes trial.