Rey mentions to Luke that the FO will control “all the major systems within weeks.” That’s what I had in mind, anyway.
I like that the movie aknowledges what taking “control of the galaxy” means with that line from Rey, but it never really delves into that, as it’s instead focused on Snoke taking care of the remaining threats before assuming control, so for the crawl I think just saying “control of the galaxy” would be more clear and to the point.
That’s just it, evidently those lost students have nothing to do with the Knights of Ren according to canon, although I think that was RJ’s intentions with that dialogue. I imagine he’d have had the scene go about as we have it in V5 were the Knights of Ren not introduced as a concept in TFA.
The comic book that shows what happened right after the slaughter appears to retcon this and tuck the inconsistencies away.
The thing is we’re hearing Luke’s perspective of events, who was unconscious while it all happened. He woke up, saw the temple on fire and some of his students dead, so he figured Ben had slaughtered them and left with the others. We know from the rest of the film that Luke’s not a reliable narrator (and that would be doubly true for events he didn’t even witness), that’s the whole point of the flashback scenes so any inconsistency with what “really happened” in some comic isn’t really an issue.
Kylo tells Rey that he “destroyed his temple”, but he never tells his side of what happened with the students, it’s supposed to be left ambiguous and we’re meant to wonder how it all really happened, the fact not all of Luke’s students were “slaughtered” really drives home that we’re not told the whole story. If anything the comic expands on that by revealing the “truth” behind those students that vanished with Ben. Though I don’t really care for the way it was handled, and I also think it’s fair to ignore such ancillary material and headcannon they’re Ren’s Knights or whatever else.