Star Wars Episode VIII director Rian Johnson asked J.J. Abrams to switch out one thing at the end of Episode VII.
If you have not seen Star Wars: The Force Awakens at this point ... nah, I'm not even gonna bother with the spoiler warning, because if you haven't seen it by now you're probably not even reading this.
Anyway, at the end of The Force Awakens, Rey (Daisy Ridley) finds the exiled Luke Skywalker (Mark Hamill) on Ach-To and silently holds out his lightsaber to him ... and there they stand as the film cuts to the credits and Abrams moves off the stage to make way for Johnson to pick up the story in Episode VIII.
Now Johnson already knew how The Force Awakens would end, seeing that his film was going to pick up right where its predecessor left off. But when he saw the scene as filmed, he asked Abrams to change one thing, as he revealed in a new interview with EW:
"I asked if R2 could come with Rey, and if BB-8 could stay behind with the Resistance. Originally it was BB-8 who went with Rey, which makes sense for the story in a way. But I asked, ‘Can you do me this solid and switch the droids?’”
Since it was R2-D2 who reactivated himself near the end of The Force Awakens and provided the final clues necessary to locate Luke, I think it sort of did make sense for Johnson to request that. It also, as he explained, provided a little bit of an echo to The Empire Strikes Back, a film in which Luke and R2 spend a lot of time together, either alone or with Yoda.
Finally, Johnson reasoned, it would be nice for Luke to see his beloved old companion, a familiar face (so to speak) accompanying the seemingly unknown Rey. And most importantly, that ending paved the way for Johnson to move Luke and R2 into the center of the story in The Last Jedi:
"Figuring out where (Luke's) head was at was the very first thing I had to do when writing the movie. I had to crack this. And it had to be something for me that first and foremost made sense. Why did Luke Skywalker go off to this island? That was the starting point, and that’s what the entire movie explores."
We've gotten just little hints about Luke's vanishing act in The Force Awakens -- his failed school to train new Jedi, the corruption of Ben Solo into Kylo Ren and the rise of the First Order are all more or less contributing factors -- but we have still not heard why he decided to flee instead of stay and fight. “There has to be a good reason that makes sense to him," Johnson argued. "And to some degree makes sense to us.”
No doubt we'll learn that reason when Star Wars: The Last Jedi opens on December 15.