In making the film, Buñuel added personal memories of his sister Conchita's paranoid husband who once mistakenly thought he saw Buñuel making vulgar faces at him on the street and went home to get his gun. He was stopped when Buñuel's family finally convinced him that Buñuel was living in Zaragoza at the time.
Buñuel has stated that he was disappointed by the film overall, but proud that French psychoanalyst Jacques Lacan was known to screen the film for his students as an example of paranoia.
Shot in three weeks.
An influence for Alfred Hitchcock's Vertigo.
The film gets continuously visually darker as the run time goes by.