At the end of the film, when Moraldo is saying good-bye to the young boy from the train, his "Good-by, Guido" is actually the dubbed voice of director, Fredrico Fellini. It is believed that Fellini did this to emphasize the fact that the film was autobiographical.
The part for 'Sergio Natali' was originally offered to the great Italian director, 'Vittorio de Sica'. He politely declined as he was concerned that the character's homosexuality might mark the director himself as a homosexual.