The film was shot on location in Barcelona, Spain, and on the Isle of Wight, England, including Ryde, Ryde Pier, the Military Road, and aboard the ship Red Osprey.

The hospital's exterior scenes were actually filmed at Bearwood House in Berkshire, England, standing in for the fictional Mercy Falls hospital on the Isle of Wight.

The Sleeping Beauty animated short shown to the children on a projector in the film was specially created for this movie rather than being an existing production.

The film had its premiere at the Venice Film Festival on 2 September 2005 before receiving a theatrical release in Spain on 14 October 2005.

Ivana Baquero, who plays Mandy Phillips in the film, would go on to star as the lead in Guillermo del Toro's Pan's Labyrinth, another Spanish genre film.