I was wrong. Despite the official StarWars Twitter claim they had the robot bb-8 on the dunes for filming, a documentary says the full robot version wasn’t done until the red carpet. However I have found videos of a large bb-8 rolling on sand. The small toy ones cannot roll on sand. (Which isn’t surprising because most toy cars can’t run on sand despite full size being able to.)
Yes many were stick puppets. Some were trikes.
So did the mechanical ball roll itself uphill?
I was wrong. Despite the official StarWars Twitter claim they had the robot bb-8 on the dunes for filming, a documentary says the full robot version wasn’t done until the red carpet. However I have found videos of a large bb-8 rolling on sand. The small toy ones cannot roll on sand. (Which isn’t surprising because most toy cars can’t run on sand despite full size being able to.)