Feral cat population is really only at
Disneyland. I'm sure a few have found their way to Disney World but at Disneyland they participate in a TNR program, have shelters built in, and even feed the cats to make sure they aren't starving. Disney World has a ton of critters lurking about. When I was a CM and park clearing my coworker stepped on something that squeaked and ran away. It was massive! We tried to convince ourselves that it a cute rabbit but we both new it was a rat. They usually stay hidden during park hours but some get way too comfortable with people and then they have to be taken care of.
I have heard the shop by Splash Mountain is the worst for animal activity.