Star Wars: The Last Jedi - 39 Things We Learned From The Director's Commentary

5. Force Projection

Luke's return is one of the major moments of the film, but also one of its biggest rug-pulls. The reason Luke came back as a projection was that Johnson needed him to return and face Kylo, but couldn't have either of them kill the other. He wanted Luke's death to be the opposite of Han's in The Force Awakens, and to be peaceful and on his terms.

They took out all the sound so Luke doesn't make any noise when he interacts with anything, and had his footsteps erased, to make it as fair as possible on the audience in terms of him not being there. The moment of Luke brushing the dirt off his shoulders is "a little cheeky", with the aim to shake the gravity up a little bit, while Johnson likes the idea that it might be a callback to his and Kylo's training together. He had to come up with a couple of clashes that felt dramatic, viewers but would realise they didn't actually make contact with each other.