Viggo Mortensen did not intend to act in the film. "Late in the game", the actor who had originally been cast as Holger left to work on a different project. Vicky Krieps suggested he take the role himself.
Vivienne makes a living selling flowers, as did writer-director Viggo Mortensen when he was a young man living in Denmark.
On casting Vicky Krieps, Viggo Mortensen said, "I thought she would be great as this character. Very quiet but with a particular point of view. I needed someone I could believe was from the 19th century, and I don't believe that about all actresses I see for various reasons."
The knight that appears in young Vivienne's visions carries a familiar sword: Anduril, Aragorn's sword from Le Seigneur des anneaux : Le Retour du roi (2003), which was gifted to Viggo Mortensen by Peter Jackson at the end of filming.
Four languages are spoken in the film: English, French, Spanish and Danish. On several occasions, languages are mixed within the same line of dialogue.