When Adelaide finds herself back in the hall of mirrors and she first opens the door into the tunnels, the first thing she sees is a rabbit coming out, and then down the rabbit hole she goes, as in Alice in Wonderland.
We also see daughter Zora sporting a t-shirt with a rabbit on it early in the film.
Once again, we’re dealing with the idea that an entirely new world we weren’t aware of has existed beneath us all this time.
We look at them as the opening credits run, and we learn they were the primary food that the tethered had to eat.