Several of the clowns and journalists in the last scene are really fans of Álex de la Iglesia. They were invited by the director himself for supporting him through his official website.
In a 2005 interview, director Álex de la Iglesia said that the name of the movie "Crimen Ferpecto" ("Ferpect Crime") is an homage to Dial M for Murder (1954), which is known in Spain as "Crimen Perfecto" ("Perfect Crime"). Also, 'Dial M for Murder' is one of the movies Rafael bought to plan the crime.
(at around 20 mins) The dialogue between Rafael and Roxanne about his past was supposed to be a discussion over dinner but Kira Miró suggested that the director turned it into a sex scene for comical purpose.
Visa d'exploitation en France : #111798