Continuity mistake: When he puts the pins in her eyes, evey time it is shown it's different - sometimes they are all covered in blood, sometimes only some of them or one, and sometimes there's no blood at all.
Opera (1987)
1 mistake - chronological order
Directed by: Dario Argento
Starring: Daria Nicolodi, Ian Charleson, Cristina Marsillach, Urbano Barberini
Marco: I think it's unwise to use movies as a guide for reality. Don't you, Inspector?
Inspector Alan Santini: Depends what you mean by reality.