C-3PO definitivamente viu Luke. Mas acho que o C-3PO suspeita que algo está errado, porque pouco antes de Luke sair para enfrentar a Primeira Ordem:
Luke turns around to C-3PO and winks broadly at the robot. And C-3PO has a confused look (for a robot anyway) on its face.
Você não pode perder esta cena.
Além disso, @Mhavhavity diz em sua resposta que
Luke deflected Kylo's lightsaber with his own.
Mas eu não me lembro de que na cena da luta (pelo menos na minha primeira exibição), o que eu lembro de ver é:
Luke emerging unscathed from all the firepower that the First Order threw at "him" and then avoiding Kylo's strikes during their face-to-face "battle". He also didn't leave any footprints on the planet's red and white salt surface while walking.
Eu estou querendo saber se não era tanto um truque mental (que teria afetado apenas criaturas vivas), tanto quanto era um
Projection or hologram. Which robots can see.
Atualização: como apontado nos comentários abaixo, o dado pode ser uma anomalia. Mas meu palpite é que:
When Luke walks into the Resistance base, he doesn't make "contact" with anyone but Leia. He talks to her, kisses her lightly on the forehead, and leaves the dice from the Falcon in her hand. After Luke disappears, when Kylo searches the base, he finds the dice, which immediately disappears from his hands, leaving Kylo either frustrated or sorrowful (it's unclear which.)
Since Leia is the only person Luke comes into physical "contact" with, my suspicion is that Leia somehow understood what Luke was doing (even though she was not a Jedi, she was strong in the Force as well), or at least suspected something like C-3P0 does.
That would also explain why Leia left the dice behind, to make sure that Kylo saw it before it disappeared.