The first and only movie ever made with a sequence filmed in the Corta Atalaya depth, one of the biggest open cast mines in the world (1,200 m. long, 906 m. wide and 325 m. deep).
The character of Felix Cadecq (played by 'Manuel Solàs') is a tribute to the real science fiction writer Philip K. Dick, and his lecture at the Sci-Fi Congress is based on the famous lecture K. Dick did in Metz (France), 1977.
Alfonso Merelo, who plays the master of ceremonies at the science fiction conference is a science fiction conventions organizer in true life.
Félix Cadecq's book titles The second lie and The time of Venus are related to Philip K. Dick's novels The Penultimate Truth and Martian Time-Slip.
Tony and Néstor, the psychiatrist, mention quite a few times brainwashing, a mental control technique, frequently used by 20th Century totalitarian regimes and applied on numerous occasions (and, usually, in an illegal way) to the reprogramming for liberated patients of coercive sects.