Johnson's fingerprints are all over the film creatively, of course, and in a couple of cases his voice and body are used in the film, but even that's not the full extent of his contributions. At one point he also took on the role of impromptu prop distresser.
For the scene in which Kylo Ren, enraged after Snoke dresses him down, decides to smash his helmet against the wall of a First Order elevator, Johnson wasn't sure he'd gotten the exact look he wanted for the helmet itself. So, instead of moving on to the next scene, he decided to spend a few minutes blowing off some steam by destroying to prop.
"We actually got a take where it was just kind of split in half, and that was gonna be it," he said on the commentary track. "Then they were starting to take the camera away, and I was like 'Uh, wait, let's try one where it's totally smashed,' and I just literally started stomping on it with both feet until it was shattered, and that's what we ended up using."
