Consider the following scenario. A person left his home in Eretz Yisrael to go to Chutz L'Aretz for Pesach. He remembered before the zman issur in Chutz L'Aretz that there was a piece of challah ...
May the sell of chometz be done with a young gentile that in Judaism would be considered a "katan" in terms of halacha and therefore perhaps wouldn't be able to have his buying and selling be "valid" ...
I can't imagine it has never come up before: Someone sells their chometz before Pesach to a non-Jew. On Pesach the non-Jew dies. What happens now?