Lluís Homar and Fernando Cayo played King Juan Carlos I in different TV mini-series. The first one was in 23-F: El día más difícil del Rey (2009) and the second was in 20-N: Los últimos días de Franco (2008) and Adolfo Suárez (2010).
Fernando Cayo and Roger Príncep were father and son in other Spanish big hit, Das Waisenhaus (2007).
The events of the movie are based on real stories that Emilio Aragón heard in the middle 90's during the production of Médico de familia (1995) TV series. Veteran actors who did guest appearances in the family show told experiences lived in the Francoist Regime (1939-1975) in the set about the life in these years. Aragón compiled all it later, mixing to create the plot of the movie.