Undoing a Vote
There is a very brief window where you can undo a vote which allows you to take back a vote you accidently cast. After a brief time, it is "locked in" until the post is edited.
I see an old vote where the answer has been edited. I accidently click which undoes the vote. Oops. I can't immediately click again to re-do the vote. The system says the vote is too old.