The scene is part of the third trailer in our handy compilation playing here.
As Rey stares up defiantly, flashes of light illuminate a hooded figure who appears to be strapped into some sort of life support machine. Listen carefully and you can hear Palpatine chuckle with glee and disdain at the naive figure before him.
This scene supports the mounting leaks and reports which talk about a finale on mystery new planet Exogol.
The flashes of light and dark cavernous setting also match the shots of Kylo Ren. It is being heavily implied he will join Rey in her battle against Palpatine.
source: express.co.uk