Those of us with cats and/or house rabbits, here's all you need to know about how to prep for them (feel free to add info!)
Emergency Preparedness fot Cats (not in order):
Get your cat accustomed to their carrier via making it comfy and cozy and leaving it out. This way when you need to leave, they won't fight you on getting in it.
Block off the "under" areas. Take a look around your house and block off any area that a cat could hide under (especially the bed). Good suggestion was utilizing chicken wire. I personally just have a ton of stuff packed tightly that is essentially unmovable for my cats.
Consider harness training, but do not allow your cat out of the carrier while in the car as they can freak out and go under pedals. Mine personally preferred shoving herself between the dashboard and windshield.
Have a dedicated go bag for your cats. This should include their "holy grail food" in case they are stressed and do not want to eat. Also store a heavily used by them blanket, so when you get to your destination they have something around to recognize their scent. Consider doing the same with a shirt of yours. Don't forget collapsible or extra bowls for food and water in their carrier.
General consensus on here is dry food doesn't last awhile, so rotate stock and keep however much extra on hand you can without risking it perishing. Canned wet food is essentially the same as canned human food, so stock up on that as well. Do not forget to add them in your water prep plans, whatever they are. Don't forget to stock litter as well!
Store important vet documents in their bag, update microchips regularly, and keep a physical photo of each pet in case you need to make lost posters.
Add a basic first aid kit: Benadryl (Allergic reaction), Pill Pockets, Beard Trimmers (Exposing wounds under fur), Betadine (Clean wounds), Saline eye wash, Towlettes, Bandages, Gauze, Kwik Stop, Flea comb, Pill cutter, Tick hook
Keep a minimum 3 day supply of any med your cat is currently taking (most vets will supply 3 days extra but not a whole month)
Emergency Preparedness for House Rabbits:
The above rules apply, minus the harness training. Get them used to their carrier, block off your "unders", give them their own bag. Stock and rotate food, don't forget water, and store important info in their bag. Keep a first aid kit, and have as much extra of any long-term medication they are on you can.
Rabbits can live without their veggies, but not without their pellets and hay. Both can last a very long time, as can most rabbit treats (Oxbow banana chips especially). Stock up on their favorite pellets and hay: and know, Tractor Supply hay is much much cheaper for essentially the same quality as Oxbow. We all know rabbits love their hay, hoard it & rotate.
Even if they are freeroam, add a collapsible playpen as the metal pens are too hard to lug around. Alternatively, keep a metal one in your trunk at all times.
Make the same first aid kit as you would for a cat, but add Simenthicone (Mylicon), syringes, and Critical Care. Get your vet's opinion on dosages and write them down for future use.
And for the love of all things good, don't just abandon or eat them when the going gets tough. They love you, and they deserve the same care and respect you give yourself.
Good luck.