Players expect consistency in games. If you establish a rule or a piece of setting information early on, expect it to be brought up by the players repeatedly in the future.
The natural corollary of this is only mention things that you're happy for your players to keep reminding you of.
Commentary by memnarch (who has not seen the movie)
Hahahahaha! They're almost actually arm-wrestling here too! If there wasn't a writer on the movie who was a fan of the comic and hoped for this sort of scene here, I would be shocked.
It's an interesting setting choice of having the throne in the background here. I'd thought it was strange that Snoke's bottom half was still nicely seated while the top had vanished. Then I realized that no, it's burning on the floor there, looking just like the burning red wall bits. Which I guess was just fabric or something, since that's all burnt now too. There's probably some symbolism in the whole framing, but I can't think what it'd be here.
Anyway, the outcome of the Force Arm-Wrestle seems pretty obvious. It's a little hard to tell which way the lightsaber is pointing in the counter-grab panel, but it's very obvious in the last one. Plus, between the two of them, Kylo is much better positioned to have a new hand installed before the end of the movie. We've had the hand jokes, we've even seen this lightsaber switched on at a distance; I bet that the blade is going to go straight through Kylo's palm.
Transcript
GM: Sally? Pete? You’re still in Snoke’s throne room.
Kylo Ren: So you were going to turn on me all along. You’ve played your hand too soon.
Rey: I wanted to do it while I still had two hands left.
Kylo Ren: But now I have your weapon.
Rey: Force Pull! I try to surprise him!
GM: Make opposed rolls, Rey’s Force Pull against Kylo’s Force Sense.
Rey: 13.
Kylo Ren: 18!
GM: Kylo senses the motion in time to react.
Kylo Ren: You know what this means... !?
Kylo Ren and Rey: Force Arm-Wrestle!
GM: I cannot believe that came up again organically.
Kylo Ren: Any coherent sequel needs callbacks!
GM: If the original was coherent, maybe.