During the preparation, director László Nemes, cinematographer Mátyás Erdély and production designer László Rajk made a pledge to stick to certain rules, or a "dogma", which included:
- The film cannot look beautiful.
- The film cannot look appealing.
- We cannot make a horror film.
- Staying with Saul means not going beyond his own field of vision, hearing, or presence.
- The camera is his companion, it stays with him throughout this hell.
Shot in the now unusual Academy aspect ratio of 1.375:1 to achieve a portrait-like narrow field of vision and to be close to the aspect ratio used in the 1940s.
The film took five months of sound design, where human voices in eight languages were recorded and attached to the original recording of the production. Sound designer Tamás Zányi described the sound in the film "as a sort of acoustic counterpoint to the intentionally narrowed imagery".
Out of a whim, director László Nemes invited his friend Géza Röhrig, a Hungarian poet living in Brooklyn, to audition for a supporting role in the film. Just as the filmmakers were about to cast another actor as Saul, however, they found Röhrig perfect for the lead role. Röhrig didn't act on camera since the 1980s and this is his feature film debut.