The scene in question is reportedly a before and after explanation of the events that led up to Luke placing his robotic hand on R2-D2, as was seen in all the Force Awakens trailers and included in Rey’s initial Force Vision.
Making Star Wars speculates that Rey’s entire Force Vision had been planned out for Star Wars 7, which would have explained what happened to Luke leading up to his self-imposed exile on Ahch-To.
Rey will have more Force Visions in Star Wars: Episode VIII, and they will reportedly continue the flashback scenes that were revealed in The Force Awakens.
It was said during the release of The Force Awakens that Rey’s initial Force Vision was supposed to bring her to Bespin, where she would have seen a flashback to Luke and Darth Vader’s iconic first lightsaber duel.