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.)
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.)