This film has a previous episode shot in the short Paraíso en llamas (2020), also a docufiction that depicts a final episode within the siege of Malaga during Spanish Civil War. The whole story is inspired by the actual memories and depictions from all the 8 characters in the film. Only 3 of them appear in "Paraiso en llamas", while the full background story relies on other foreign visitors to Malaga in the 7 months between July 1936 and February 1937 in which the city started a revolution in the bloody context of a civil war.
The song of the soldiers, a traditional song from Spanish Civil War, is a flamenco version (soleares) arranged by Isabel Royán and sung by La Mari from Chambao, a local band with success all over Spain.
Archival footage from the Italian army conquering the city of Málaga on February 8th 1937 on behalf of Franco's forces comes from journalists within the C.T.V. battalion. Apart from soldiers, tanks and artillery, they developed a very organized propaganda campaign of the fascists exploits in Spain for the Italian audience. Their first newsreel is precisely "La liberazione de Malaga" and has been restored by the Istituto Luce. The anecdotes told by the character of Bonaventura Caloro are taken from several of the Italian journalists within this Uffizio Stampa.
The film is dedicated to Regina Álvarez Lorenzo co-writer of the script, and also to Willard C. Frank, history advisor and one of the main characters of Operación Úrsula (El misterio del submarino C-3) (2006) previous documentary of José Antonio Hergueta also dealing with events of Spanish Civil War in Málaga. Willard C. Frank shared with Hergueta the stories of these international witnesses, some of which had not yet been published in Spain in 2005.
One of the mentioned characters who visits Gerald Brenan's and Gamel Woolsey's home in Málaga is English writer Humphrey Slater who disappeared mysteriously after the war in Spain, but before wrote several novels: "The heretics" is inspired by the events in July 1936, coup d'etat and popular revolution, and Conspirator (1949) adapted for the screen in 1949, directed by Victor Saville and starred by Robert Taylor and Elizabeth Taylor