I have a smaller rubbermaid tote thing that I keep all of my animals supplies in (meds, brushes, nail clippers, shampoos, flea, heartworm meds, extra collars etc..) it is always kept right near my door.

I keep my leashes hanging on a hook next to the door (and of course spares in both of my vehicles).

I have a room that is just for my ferrets & hamsters & they have all of their carriers (plus a few extras) set up on top of their cages & I keep the doors open on the carriers too, all ready to load if needed.

I also keep one carrier (big enough for both cats in case I can't get to the ferrets room for another carrier) next to the door at all times.

I have extra water/food dishes already installed on the carriers.

I have a bag (beach bag size) filled with extra toys, treats, more leashes & vitamins that I always keep with me, it goes everywhere with me!

I also keep at least one large bowl in each vehicle.

The only thing I don't have made up, ready to go is food. I tried it before & had a small bag made up in their bags but kept forgetting to change it so it stays fresh.
And now I have more animals & to have all that on hand is a lot of stuff. I guess we'd have to get to a store & get some or they'd have to live off of their treats &/or people food for a day or so until we could get to a store.