Always be alert for traps. And be exhaustive when listing the things you're keeping an eye out for.
You don't want to hear a GM to say, "But you weren't looking for a shrunken minotaur disguised as a St Bernard."
Commentary by memnarch (who has not seen the movie)
Debatably, it's not unstable terrain, just one that's not meant for normal human movement if this glitch is constantly here. A cliff wouldn't count as unstable terrain on its own after all, and you can still fall off of it if you're not careful. This is definitely more interesting than a slimy pit though, so that's something at least. It might even end up being more interesting than the cave tree at this rate.
With the camera change, I wonder if this is meant to show that Rey is getting pulled into the crystal mirror in the movie. It's fascinating how all of the reflections are pointing in the same direction. Normal reflections would alternate I would think, so this would need to be meaningful either way. Maybe there's something meaningful in the number of reflections as well? It looks like there's only the five, but I can't think of anything in Star Wars that has five as a meaningful value.
Rey: Well. I look around the cave.
GM: A polished crystal surface shows your faint reflection.
Rey: I approach carefully. Alert for any sudden attacks.
Rey: Or unstable terrain.
Rey: Or traps.
GM: You don’t notice anything like that.
Rey: I touch the surface.
GM: Instantly you are drawn into a dark corridor containing multiple copies of yourself.
Rey: I was alert!!
GM: Not for this. This is a glitch in the space-time continuum.
Rey: The space-time continuum counts as terrain!