Director 'Bernardo Bertolucci' contemplated filming an explicit love scene between mother and son characters played by Jill Clayburgh and Matthew Barry but this was dropped.
The Italian producers were so outraged by this film's story line that they forbid the director to shoot the film with a local cast and as such the roles played by Jill Clayburgh and Matthew Barry had to be changed to be Americans.
The movie was a Bertolucci family affair. Giovanni Bertolucci produced the film; Giuseppe Bertolucci was a writer and an uncredited 2nd assistant director; Lilletta Bertolucci was a unit publicist in Italy; Bernardo Bertolucci was a writer and director whilst his wife Clare Peploe was also a writer.
The film's "Luna" / "La Luna" title (translates from the Italian language as "Moon" / "The Moon") was derived from one of director Bernardo Bertolucci's earliest memories where he looked up to the face of his mother and then pivoted across to the moon and then saw the two images blend into one.
Playing an opera singer in this movie, actress Jill Clayburgh never actually sings, all her performances were mimed.