I'm sure we've done this, but wth... Here is the whole scene from the script.
Rey is heartsick, but she turns as she hears the sound of a young girl in anguish, crying. She follows the sound into the castle, turning so she can't see that Finn has looked back at her one last time.
INT. MAZ' CASTLE - BASEMENT CORRIDOR - DAY
Rey steps down into the basement corridor. BB-8 follows her. Walking carefully and confused, she is not sure why she's down here. She can hear the echoing sounds of a young girl crying. She heads down the hall... to the very end, where there is a door. It is almost as if a SOULFUL VIBRATION draws her closer. She looks at the door lock -- AND THE DOOR OPENS. Hesitant, Rey enters.
INT. MAZ'S CASTLE - CRYPT ROOM - DAY
Rey moves into the dark, small, vaulted storage room. Old treasures line the floors and walls, but there is something specific Rey is drawn to: on a table, an old wooden BOX.
She moves to it, unsure, afraid, as if an energy from inside the box has been calling her here. BB-8 nervously follows.
Rey reaches out, very slowly, to touch the box. A moment heavy with tension.
Rey OPENS THE BOX and sees inside Luke Skywalker's original lightsaber. With hesitation, she reaches towards it, but she cannot resist. As her hand makes contact with it, there is the piercing sound of a lightsaber igniting. She moves her hand away, as REY HEARS A MECHANICAL BREATHING sound.
The CAMERA MOVES, LIGHTING CHANGES -- and we see behind her something impossible: a HALLWAY OF FROM DEEP INSIDE CLOUD CITY. Disembodied voices fill the air.
YOUNG GIRL
NO!
She stands -- looks around, confused by all she sees and hears. -- Turns and sees, through a DOORWAY.
We follow Rey and she runs down the corridor, but it all TILTS -- TURNS -- and she lands on the WALL -- which is now the GROUND -- dried GRASS.
She turns to look -- we PIVOT -- and see a BURNING TEMPLE AT NIGHT. We PAN to:
R2-D2 -- who watches the flames -- and a MAN appears (LUKE, whose face we do not see). He falls to his knees, reaches out to the droid -- with a MECHANICAL RIGHT HAND.
We PUSH IN ON REY as RAIN BEGINS -- and DAY TURNS TO NIGHT -- and she LOOKS UP -- we TILT UP -- To see we're LOOKING UP AT A WARRIOR as he is STABBED BY A FIERY LIGHTSABER! He screams and falls to the ground -- we FOLLOW HIM, revealing Rey again, now in a nighttime battlefield. She gets to her feet, frightened by what she sees. We PIVOT AROUND HER to REVEAL KYLO REN, and the six other KNIGHTS OF REN, who flank him!
Come back around to Rey, soaking now, as the RAIN STOPS and SUNLIGHT illuminates her -- she turns to look -- we PIVOT -- and see...
A little girl. Rey as a child. She is sobbing, hysterical.
Unkar Plutt's meaty hand holds her thin arm. She is on Jakku, watching a starship fly into the sky, abandoning her.
YOUNG GIRL
No, come back!
UNKAR PLUTT
Quiet, girl!
The ship flies towards the desert sun, which is strangely eclipsed, as if being eaten by darkness. Rey looks around her to see she is..
In a NIGHTTIME, BARREN, SNOWY WOODS. She's losing her mind, confounded and lost and she gets to her feet, her breath seen in the frigid air -- and then: THE SOUND OF CLASHING LIGHTSABERS! She moves through the woods, toward the sound. Rey runs, heart pounding, when KYLO REN EMERGES FROM BEHINDA TREE! She stops, SCREAMS, FALLS BACK and LANDS IN:
INT. MAZ' CASTLE - BASEMENT CORRIDOR - DAY
She falls back, out of the room, suddenly sitting in the hall, out of breath, alarmed and perplexed.
---
Tough to find a clear common thread. No one party, including the lightsaber, is present at all of these events. Some are in the past. Some are in the future. It's not sequential.
Really the Knights of Ren image is key and the most unknown... Could be the past or future and there is evidence to support both. Assuming the burning temple is the aftermath of Ben Solo's betrayal, we know all of the other events. The only other mystery is who left Rey with Plutt, and why... But obviously that's the big one.