You can prepare a box or bag of supplies you might need, and for things that you can't keep in there like maybe the hay and pellets, add them to a list of things to grab last minute. You'll need a pen or cage, tarp or flooring of some sort if using a pen, litter box, litter, food and water dish, possibly jug of water, food pellets, hay, small dust pan/broom, cleaning supplies, rabbit first aid supplies(gas drops, critical care, syringes, etc).