Lots of red and yellow balloons and streamers make a perfect backdrop for a carnival kitty party.
Make colorful signs to hang above each game booth and stand.
Put up a brightly colored tent or tarp (or decorate a plain one) for the food stations and bring out small tables and several chairs incase kids (or parents) want to take a break in the shade. Decorate a large appliance box in red and yellow and make it into a ticket booth. The kids can exchange their “money” for tickets.