When the writer told the little girl who plays the blind orphan that she had pretty eyes, she replied, "Oh, do you like them? I picked them out myself!" What he didn't know: She was diagnosed at a very young age with a degenerative eye disease that was going to leave her blind. One of the last things her parents did while she could still see was let her see a big selection of glass eyes and choose the ones she wanted.
Overawed at being in the company of acting veteran Geraldine Chaplin, J.A. Bayona broke the ice on her first day by hiding under a bed and grabbing her leg when she knelt down in the dark. Chaplin's scream in the film is one of genuine surprise.
The orphanage was an old colonial house in the town of Llanes. As a lot of J.A. Bayona's cinematic plans were impossible to achieve on location, several parts of the house had to be recreated on a soundstage. In fact, over 80% of the film was shot in a studio.
One of the orphaned children Laura identifies in the photo she is shown she calls "Guillermo", an obvious nod to the Producer of the film. You also see his name during the scene where the window behind Laura smashes and she reveals the names of the old orphans and the dolls.
'Sergio G. Sanchez' wrote the screenplay in 1996, ending up in J.A. Bayona's lap in 2004. Bayona then approached his friend, Guillermo del Toro, to help him produce the film and double the budget and shooting schedule.