This is so true! This happened to us once - we had double-hung windows, opened just a crack at the top. It was enough to blow our bedroom door shut, with the cats inside! Luckily, we were only gone overnight, and they did have access to water (in the toilet!) but they didn't have a litter box. The cats were quite creative, though - they used our bed as their litter box, and carefully pulled the edges of the comforter over their "mess". (At least we could wash the comforter and sheets!)We have 2 cats and even though we have very reliable pet-sitters, we make sure that a bathroom door is propped open and the toilet lid is up, just in case something happens and the cats are not cared for. This is especially important in the summer. A corollary to this is to make sure room doors are either closed tightly or propped slightly (we usually put towels over the top of the door) to prevent a pet from accidentally being closed in a room (especially if the windows are open a crack) .
Make sure your children have flushed the toilets.