Well that's a terrible place to exist.
Imagine what a bastard Santa Clause would be. Sneaking into houses and stealing children's favorite toys.
However, in 70 years Hitler will come back to life, reserect millions of people. LIberate France and the low countries then fuck off back to austria.
So either way we end up shitting ourselves?
I googled mirror universe and the first links is a Wikipedia page about Star Trek: "The Mirror Universe is a parallel universe in which the plots of several Star Trek television episodes take place."
What if we're in the backwards universe?