I have snapshots of each of my furbutts along with copies of their shot record and rabies information in a yellow envelope that goes everywhere I go.........it literally stays in the car. On the back of each photo, I put their name, dob, my name, address and phone number!!! Nothing better than a snapshot to ID a dog running on the loose that has escaped to people in the area.
Maybe you already carry a flashlight but that is also always in my car. I also carry a gallon of water just in case they get "dirty" feet from a dog walk area. I carry a 13x9x2 inch pan to pour the water in and you get all four clean all at once and then it is just a matter of drying them little paws. I also carry a plastic shower curtain (From the dollar store) to put in the trunk to set them on to contain them while all three get their feet dipped into the water ............ empty the pan, dry the feet and we are good to go and it keeps my trunk "dry."