If A Wizard Did It, blame this guy.
Hand Wave plotholes, inconsistencies and anachronisms with one simple statement: "A Wizard Did It." Well, SOME works take this a step further, by introducing you to the exact wizard behind it. The Wizard that Did It, if you will. Unmarked spoilers beyond, since this is generally a plot twist, with the exception of the trope namer.
Examples:Anime and Manga Film