'Carlos Iglesias', the director, writer and main actor of this film, is the son of Spaniards who migrated to Switzerland in the 60s and returned to Spain six years later. The movie is almost biographical, with Carlos Iglesias playing a character equivalent to his father.
The house Martin and his wife rent in the film is the same house that 'Carlos Iglesias'' parents rented while living in Switzerland. When looking for filming locations, he asked the owner about it and got told that the floor had been free for a week and was therefore available for filming. He used it, and spent lunch breaks in the room he occupied as a child.
The scene where children throw stones at a dog is inspired by a real event from Carlos Iglesias' childhood. He witnessed how several children killed, using a lead pipe, a pair of dogs that had become stuck after copulating.