If you watch the film with headphones, every time Baby wears just one earbud you'll also hear his music in only that one ear.
Director Edgar Wright once parked his car in a parking garage, only to realise that, by complete coincidence, the car next to him had a stylised "BABY ON BOARD" sign, with Baby's (Ansel Elgort) face taken from the film's poster. Wright left a note on the car's windshield that read, "From the director of Baby Driver, I approve!!!", complete with his signature.
The studio pressured Edgar Wright to cut the foot chase scene because the movie was starting to go over-budget. Wright deferred a portion of his directing fee to ensure the scene was completed.
The Mike Myers masks actually were supposed to be the masks of Michael Myers from the Halloween series but the producers were unable to obtain legal permission. Edgar Wright then reached out to the comedian Mike Myers about using masks of his likeness instead, who thought the scene was funny and gave his blessing. This is ironic because the original Michael Meyers masks were also masks obtained without getting the proper permission. John Carpenter bought a William Shatner/Captain Kirk mask from a Halloween store, and painted it white to give it a creepy look.
To create action sequences synchronized to music required extensive preparation. Edgar Wright selected what music he wanted prior to the script being written, so the screenplay could match the timing of the song precisely. For instance, if a song was two and a half minutes long, Wright would pen two and a half pages of descriptive action. Wright then had a sound designer take the music tracks he selected and add the sound effects described in the script, such as tire screeches, gunshots or vocal clips, in rhythm with the song. These sound files were given to storyboard artists, who under Wright's direction created an animatic with visuals designed to reflect the events of the script in time with the sound. Then the animatic and sound files were provided to the film's stunt coordinators and cinematographer, with the instruction of following them as closely as possible. Practice takes were arduously rehearsed for several days while being filmed with digital cameras, before multiple attempts of the final real takes were shot on 35mm film. Finally, the film's editor used footage from the film cameras video-assist to create a rough edit after each take to ensure the timing was correct. Even with this extensive preparation, things didn't always go perfectly: The scene where Baby rewinds a song was improvised on set when Wright found the song wouldn't be long enough to cover the scene.
Walter Hill: Provides the voice of the courtroom interpreter. Hill directed The Driver (1978), one of Edgar Wright's primary inspirations for this movie.
Edgar Wright: When Baby delivers a pizza, there is a closeup of Wright's finger pressing the doorbell button. Wright also is seen reflected in the music shop window during the first coffee run. Wright said on Twitter he was following the shot and planned to remove the reflection in post, but decided to leave it in.