When Angela (Ana Torrent) is accessing the warranty database, director Alejandro Amenábar's name appears as a warranted customer of an XT-500 video camera.
The film had a relatively small budget of P116 million - equal to about 696,000 EUROS.
Alejandro Amenábar wrote some of this film while still at University, and that University was the Complutense, as featured in this film.