The Po Office Doesn't Know Jack

I'm thinking of starting an exhibit with the above title. It would feature postal history covers where a "mistake" was made by the PO. the 1st Cover I have is a cover from "Barrauca" NM. I did find a Barranca NM I guess is still open. (comes up on Google earth) Other covers would be where the PO would have a yellow label that would read "Addresse moved, address unknown but then give a address. So show me some of yours.