Talking to MTV's Happy Sad Confused podcast, Trevorrow explained that he asked Johnson to shoot "this one extra thing while you're in this place on this day," without elaborating on what that "extra thing" or "this place" was.
Before you interpret this as Johnson taking over for Trevorrow (whom folks have been speculating might lose his "Star Wars" gig because of those terrible, terrible reviews for "The Book of Henry"), filming on "The Last Jedi" wrapped in July 2016.
Trevorrow told MTV that the communication between directors is "part of the collaborative process that exists ... There's such a genuine want to get this right from everybody, and I think that one of the misconceptions is that there's some kind of great corporate overlord that is dictating this story to everybody... The reality of it is that it's a small group of people... and none of them are corporate, all of them are creatives and all of them are genuinely, very sincerely, wanting to do the work of their lives in order to realize this."
This could potentially mean an extra scene of Carrie Fisher, who passed away in December 2016, but that's probably wishful thinking, since Kathleen Kennedy announced that "Last Jedi" would be the last film we'll see Leia in.
The as-yet untitled "Episode IX" is scheduled to start shooting next month, with a release date of May 24, 2019.