I would have developed that shot anyway. Just in case.
Also fun: forgetting to pull the darkslide. Not as frustrating as burning the sheet of film for pulling it too early, but it can be its own little hell.
I have also shot empty holders. This is why I tend to mark mine now with what they have in them. Always. As soon as I'm done loading them. And then I erase it when I'm done. And I have separate bags for empty and loaded holders. And those bags are MARKED.
I try to idiot proof as much as possible since I'm, more than not, the idiot.