About 20 years ago when we still had a pop-up I had a site with a hill. I forgot to chock the wheels. After I disconnected my van the trailer started rolling backward down the hill. Fortunately the tongue jack sunk in the ground and stopped it. Guess what I do on every site now?
Drove away from the house while still hooked to shore power. And, it was after I did a safety 'walk around.' Sometimes you look at things and don't see them. It never happened again.