And maybe the evil mirror-versions would have mustaches, just like in the "Spookyfish" episode of South Park.

Yeah they did. It's called Equestria Girls.

Yeah they did. It's called Equestria Girls.

Especially Fluttershy was such a good villain there. The way she viciously ignored Pinkie Pie gave me shivers. I didn't know she had it in her.

I guess if you want to get technical, "Return Of Harmony Pts. 1 and 2" could be considered mirror episodes, since the Mane Six are acting out the opposites of their Elements.

I guess if you want to get technical, "Return Of Harmony Pts. 1 and 2" could be considered mirror episodes, since the Mane Six are acting out the opposites of their Elements.

Right, that went in that direction. Personally, I'd want all positive elements removed from the scenario. The mirror universe thing is usually meant to be kinda cheesy.

I realize though that a good reason for not having such an episode is because MLP is not a show where you have fixed goodie-four-shoes. Everypony's dark side can be explored there.

Also, I think such an episode format is usually done towards the end of a show, when they're running out of original ideas and just try to goof around.

So as initially mentioned, anything in that direction in MLP would have to at least transform the mane cast into nightmare versions. The peculiar thing about such a format would be the fact that there is no apparent counterpart, no shining beacon, left. If the writers wanted to make it have a happy ending, which MLP should always have, the characters would have to find that light within themselves; discover it through distancing themselves so far from it that the coin flips.