So I guess I'll be the one to say it...
If we're looking for something "groundbreaking" in this episode, how about what it did—quite matter-of-factly—with gender roles?
It's pointed out to us front-and-center that the ponies with the invitations are taking their "plus ones" as
dates. Maybe it's a turn of phrase, maybe whatever—but the end result is that every couple we see at the Gala, or at least every one we spend any time with, is a same-sex pair. Sure, every one we see also has a reason we should treat it as something other than a
date date (the CMCs are going with their big sisters as kind of a sympathetic joke, like the way you'd take your mom to the prom, and Fluttershy and Tree Hugger are obviously just buddies); but the
pervasiveness of the way the couples are presented leaves you feeling that something important has been established about this world.
Whether it's saying that the Gala isn't the kind of event you'd take a romantic date to, or that romance is a completely tangential concept to the way you'd approach taking a "plus one" to a fancy dress party, or that dating in Equestria isn't even
visibly a heteronormative thing, it's quite a departure from how this sort of idea would ever have been handled in a previous era.
Discord could have brought, say, Chrysalis or Catrina or someone... but no, he stuck a top hat on the
Smooze.
