François Truffaut's reason for his character Ferrand wearing a hearing-aid (while never clearly defined as deaf) is partly expressed in a voice-over mentioning a film director is the person everyone in the crew has a question to ask. In later interviews, Truffaut explained the best way he could find to ignore some of those questions was to pass for someone hard of hearing.
As Severine (Valentina Cortese) has more and more trouble remembering her lines (blowing several takes), Ferrand eventually writes her lines on pieces of paper that can be stuck up on the set out of sight of the camera, so that she can read them. It doesn't really work here. However, Truffaut used the same trick for himself when he was having trouble remembering his English lines in Close Encounters of the Third Kind (1977).
After the release of this film, Jean-Luc Godard sent François Truffaut a letter criticizing the way the film depicts filmmaking and called him a liar for it. Godard also criticized him for pandering to the mainstream, something they were both critical of filmmakers doing when they were critics at Cahiers du Cinema. Additionally, Godard went on to say that because the film was not truth and because the film was a hit, that they should make a film together about the filmmaking process; Truffaut would produce, Godard would direct, and they would both co-write the script. Godard's return address was of Jacques Daniel-Norman, a virtually unknown filmmaker whose films were loved by Truffaut and Godard when they were film critics, hinting at a return to a simpler time. Ignoring this hint, Truffaut was insulted by the letter and responded by telling Godard that he is demeaning and pretentious and that he pretends to be poor, when in reality he was the wealthiest of their circle of friends. The response also included a line in which Truffaut flat out calls Godard a "shit". It is believed that this quarrel is what ended their lifelong friendship. Godard later regretted writing this letter, especially after Truffaut's early death in 1984 and went as far as to write a moving tribute to his former friend.
As the director Ferrand (François Truffaut) and the Cinematographer Walter (Walter Bal) are looking over promo stills of Julie Baker (Jacqueline Bisset), one remarks that he remembers her "from that movie with the car chase". This is an inside reference to the fact that five years earlier Bisset played the role of Steve McQueen's girlfriend in Bullitt (1968), a film featuring a groundbreaking car chase.
A sequence uses a scene with a cat drinking milk from a discarded room service tray from Truffaut's film The Soft Skin (1964) as its inspiration, this time showing the audience the multiple takes required to get the cat to go to the tray and drink
The film was nominated for Academy Awards for two years: As best foreign language film in 1974, and director, supporting actress (Valentina Cortese), and screenplay in 1975. This happened because the eligibility periods for foreign language film is different than other awards, and is dependent on the film's release in its originating country. Academy rules have since been amended, limiting nominations in all categories to the same year.
When Nathalie Baye first heard that Billy Wilder asked François Truffaut if he used a real script girl for the part of Joelle, she felt a bit offended as she was trying hard to be a proper actress. Later, she eventually admitted it was the best compliment she could receive.
At one point Georges Delerue (who did the score for this film and many of Truffaut's films) calls to play Ferrand a piece of music, later used in the costume ball scene. This is from Truffaut and Delerue's earlier collaboration, Two English Girls (1971). In fact the opening sequence primarily uses outtakes from Two English Girls' scoring session.
In "Meet Pamela," the film-within-the-film, Pamela (Jacqueline Bisset) explains that she met Alphonse's character after the girl he was supposed to be with in England came down with chicken pox. This is a reference to Bisset's first movie role, in Stanley Donen's "Two for the Road," where architecture student Albert Finney ends up traveling through France with English girl Audrey Hepburn after the girl he was supposed to travel with (Bisset) comes down with chicken pox.