Well, okay!  Ari gets yote into the mirror.

- into in the sense of through, apparently.

The other side is superficially the same ballroom until she looks to the exit.  It's on the opposite side from where it normally is, and the open door reveals something that's unclear at this distance but is probably not the rest of her house/castle/mansion/whatever.  Also the guy is gone.

She....goes to investigate the exit?

It leads to a sleek but not intimidating hallway with walls in charcoal grey and a delightfully plush light blue carpet.

Ahuh.  And what's down the hallway.

A door!  It opens into an expansive lounge in a similar style and theme to the hallway.  The center of it has a seating area set a few feet lower than the rest of the room, with much of its perimeter in couches; it also has a few circle chairs and bean bags.  Around the outside, there's a snack bar and a foosball table, and a few other miscellaneous items.

Probably of greater interest, though, are the several other people who open their own doors at the same moment she does.