The movie got 3 different aspect ratio format:
1. 1.33:1 for the Donald Dennis Hall silent scene.
2. 1.78:1 for all the Prologue "stage" scenes.
3. 2.35:1 for the main plot.
David Díaz got the idea for the movie after listening to the Cheap Trick song "Reach Out". He said that song inspired him for the scene were the girls wake up as hypnotize zombies.
David Díaz wanted Rafa Rodrigo to play Jaime. He also play that character on Ridiculus Mortis: Solo la muerte se flipa 2 veces (2007) before. But Rafa preferred and different character to play, so David offered him to play Osquitar.
Luis Rodrigo contribute to create most of Donald Dennis Hall's biography. He got the idea that Hall were missing at 33, just like Jesus Christ died.