The first letter of the names of each of the wooden animals that Rick Deckard carved in this movie: Rhino, Antelope, Cat, Horse, Elephant, Lion, spell "RACHEL".
David Bowie was director Denis Villeneuve's first choice for the role of Niander Wallace, but he died six months before the start of shooting. Jared Leto was cast instead because of his "similar rock star vibe," since he fronts the rock band Thirty Seconds to Mars.
To make Joi (Ana de Armas) appear more artificial, editor Joe Walker experimented by freezing her image for nine frames just before she responds to a question. That way it looked like her program paused for a split second, as if her processor was briefly occupied in coming up with an answer. However, it felt corny and it was decided that her artificiality was already convincingly communicated through her fast costume changes and transparency.
The giant Joi in the hologram advertisement was supposed to be her "default" setting, the idea being that "K" customized her voice and appearance to a less sexualized version. The advertisement version of Joi was not voiced by Ana de Armas, but first assistant editor Mary Lukasiewicz. She recorded a temporary voice-over, but the producers decided to keep it in the finished movie.
As seen in this movie, the baseline test that "K" must recite back ("A system of cells interlinked within / Cells interlinked within cells interlinked") was Ryan Gosling's idea. He employed an acting technique called "dropping in", which induced a trance-like and hypnotic effect on his performance.