by dexeron » Fri Mar 04, 2016 4:10 pm
There was one like that - but the one that could go over most terrain had to have the head on a track - and even then, like Agent quoted, really deep very fine sand could stop it.
From what I gather, they used the 7 different BB-8s for different situations: this one for close-ups and "emoting," this one for distance shots, this one for close-ups on rough terrain, etc, etc.
EDIT: my favorite bit of pre-release news was Mark Hamill gushing about being allowed to drive one of the BB-8s around the set. He was totally fanboying, and it was one of those "aw, that's awesome" moments.