re: A creepy thought...
If they had 'beefed-up' that robotic arm a little bit it could have been used like a boom on a backhoe to help push or pull its way out.
With the arm on the downhill side:
Retract-plant-[extend(push)+spin wheels]-travel-stop-retract-plant...
or
On the uphill side:
Extend-plant-[retract(pull)+spin wheels]-travel-stop-extend-plant...
It'll work, as long as it doesn't rain...