The title of the film comes from the poem Good morning, midnight by Emily Dickinson,[2] in the 2001 Italian translation by the poet and novelist Nicola Gardini, who first used the form «Buongiorno, notte».

The film's soundtrack also includes compositions by Franz Schubert, Giuseppe Verdi and Jacques Offenbach, as well as two of the most famous songs by Pink Floyd, The Great Gig in the Sky and Shine On You Crazy Diamond - for example, while Chiara sees on television the images of the partisans shot by the Nazis, while reading the Letters of condemned to death of the Italian Resistance (September 8, 1943 - April 25, 1945) - the latter also used in the trailer; The song that the former partisans sing is, instead, Fischia il vento.

In addition to the book by Anna Laura Braghetti, the director took inspiration from other sources; for example, the sentence pronounced by the leader of the brigadists, Mariano, to motivate his followers, namely that the imminent killing of Moro "is the highest act of humanity possible in a society divided into classes", is taken directly from a press release on May 10 in the courtroom at the La Marmora barracks in Turin, by the imprisoned founders of the BR, Renato Curcio and Alberto Franceschini: «...This is why we claim that the revolutionary act of justice exercised by the Red Brigades against the criminal Politician Aldo Moro, (...), is the highest act of humanity possible for the communist and revolutionary proletarians, in this class-divided society».

Some former Red Brigades, such as Morucci and Gallinari, said they had seen the film; the former also expressed a moderate appreciation: "His friends denied the authenticity of his letters while some of us, in reading them, we were associating them with those of the condemned to death of the Resistance.

[8][9] Following the statements of the jury president Mario Monicelli, which corroborated the motivations that had not convinced the jurors to assign the maximum recognition to the film ("it was impossible to convince foreigners ... this film was not up to its precedent, My Mother's Smile"), Rai Cinema announced in protest that it no longer wanted to participate in the Show:[10] a declaration right after following a meeting between the then president of the Venice Biennale, Franco Bernabè, and the CEO of Rai Cinema Giancarlo Leone.