Vesper's flying drone is either CGI or a real drone, depending on the shots. The real drone was very loud and actors couldn't concentrate on their lines when it was flying.
While visual effects are present in the movie, they are mostly there to enhance a shot with a plant or a ship, as no scenes were shot against a green screen.
It was entirely shot in Vilnius, Lithuania, mostly outdoors except the house and the farm scenes, which were shot in a studio.
Cinematographer Feliksas Abrukauskas was inspired by paintings by Vermeer and Rembrandt for the lighting.
The movie has been six years in the making for directors/writers Kristina Buozyte and Bruno Samper, who had already collaborated on Vanishing Waves (2012).