The studio reportedly forced the change to 'humans as batteries', which in my opinion is much worse (why not cows?). I have zero proof, but I think they were concerned about overlap with a famous series of sifi novels that I won't spoil by naming, but that is currently being produced by Bradley Cooper at Warner Brothers.
What is that movie/series/book all about? What does it mean? etc
The battery is a play on earlier Duracell ads. The bunny is also there. Which themselves play on the idea of the rabbit hole. It also interweaves with Toy Story from the same time period in a weird way.
It's funny how movies from the same rough period seem to be all similar underneath. Doesn't matter the studio, the director, the concept. All of it can be tied together.
It reminds me of the idea of the Gustav Gun. A giant slow ballistic trajectory launcher of projectiles on pre-laid railroads that can shoot stuff across the sea.