I’m pretty sure it was a horror movie but it had a white van maybe and a little boy or girl had to use the bathroom so the parents pulled over and the little boy or girl runs off behind a tree and then like. I am not sure if they heard a scream or if it was taking to long but the parents rushed to go find them and all they found was a white shoe with blood on it.
Rawhead Rex (1986)
Similiar to a scene in Rawhead Rex. Description is somewhat off. Girl finds dead rabbit in bushes, she screams; dad goes to help, little brother is then attacked back in the car by Rawhead.