While the stars of the film perform most of their own live singing, Marion Cotillard's operatic vocals are dubbed by Catherine Trottmann.
Simon Helberg was so eager to get the part that he became a French citizen and learned French, as the production needed more EU citizens in the cast to get EU funding. It turned out to be unnecessary as Marion Cotillard was cast in the role previously given to Rooney Mara and Michelle Williams.
Annette was not conceived as a movie; it was originally intended to be a Sparks album. Sparks had previously written and recorded a narrative musical titled 'The Seduction of Ingmar Bergman' in 2009. With an extensive cast. it proved too difficult to tour. so the band wrote Annette. The piece was being readied to release and tour when they met Leos Carax at Cannes after featured a Sparks song in his film Holy Motors (2012).
While filming in Brussels, Leos Carax's dog "Javelot" got scared by passing traffic and ran away, leading Adam Driver to post a filmed appeal on social media to help find the dog, re-tweeted by several people including Mark Hamill. Javelot was then found safe and sound in a nearby train station.