When Clerici asks the operator to connect him with Professor Quadri, the telephone number he gives is the (one-time) telephone number of Bernardo Bertolucci's idol Jean-Luc Godard. When Quadri answers the phone, Clerici recalls one of his lectures in which Quadri said "The time for reflection is over. Now is the time for action." This is the opening line in Godard's film Le Petit Soldat (1963).

The hospital that Clerici's father is at is actually the Teatro Libera (Free Theater) at the Palazzo dei Congressi in EUR, a massive complex on the outskirts of Rome that was begun as a monument to the Fascist Government. This massive, modernist white marble complex and theater have appeared in several other films and television shows.

Alberto Moravia's novel is told from an omniscient point of view. For the film adaptation, Bernardo Bertolucci chose to tell the story more from the viewpoint of the protagonist, whose memories and feelings are deliberately misleading and unreliable. Bertolucci's non-linear approach to the film's timeline only adds to the film's stream-of-consciousness feeling.

Bernardo Bertolucci was introduced by his then-girlfriend Maria Paola Maino to Alberto Moravia's novel. He was impressed by her description of the story, but because he locked in production on The Spider's Stratagem (1970), he had not actually read the novel when he pitched a film adaptation to Luigi Luraschi of Paramount Pictures, who agreed to fund and distribute the film. A month later, Bertolucci was reading the book with one hand, and writing the script with his typewriter in the other.

Bernardo Bertolucci approached Brigitte Bardot for the role of Anna Quadri before casting Dominique Sanda.

The film was in contention for the Golden Lion at the Venice Film Festival. However, a huge controversy over the inclusion of Michael Verhoeven's film O.K. (1970) resulted in the Festival being abandoned and no awards being given out.

A 2K restoration of the film was supervised by Vittorio Storaro in 2011. This forms the basis of the 2014 Blu-ray release.

The song played on phonograph record at the end of the movie is "Come l'ombra," which means "Like the Shadow." It is sung by Trio Lescano, a popular singing group of the thirties.

Jean-Louis Trinitignant regards this as the best film he appeared in before Amour in 2012.

The poem recited by Marcello while traveling on train is Gabriele D'Annunzio's "La pioggia nel pineto" (1903).

Included in the Toronto International Film Festival's Essential 100, movies every cinephile should see.

At first the film had been edited in a linear way by the usual editor Roberto Perpignani. Later Franco "Kim" Arcalli tried to edit some sequences of the film alternating past and present and changing the structure of the film. That attempt convinced Bertolucci so much that he decided to reassemble the film by Franco Arcalli, who since then became his brilliant and irreplaceable editor.

Anouk Aimée turned down a role in the film, but said in a 2007 interview that in retrospect she wished she had accepted it instead.

The fascist agent/enforcer is named Mangianello. "Manganello" is the Italian word for the bludgeon or club that became a symbol of the Black-shirts used to fight the opposition.

According to some sources, actress Isabel Adjani is one of the many extras in the dance scene.

Included among the "1001 Movies You Must See Before You Die", edited by Steven Schneider.

Ranked #77 on a 2018 BBC critic's poll of the best non-English-language films.

Among the students at Professor Quadri's house, appear Bertolucci's best friend as well as Director, Gianni Amico, also one of the iconic actors of the Brazilian "Cinema Novo", Joel Barcellos.

Italian censorship visa # 56307 delivered on 19-6-1970.

Finnish censorship visa # 80147 delivered on 21-10-1971.

The Latin phrase recited by Clerici on his way to kill the Quadris was "Animula, vagula, blandula, hospes comesque corporis", the first line of a poem attributed to the Roman emperor Hadrian.