This was an amazing episode, one of my favorites, but there was something odd that I noticed...
I'd think that the background ponies are the same age as the Mane 6, but when we see Twilight and Rarity's flashbacks, ponies such as Derpy are adults. Shouldn't they also have been fillies at that time?
I know that they probably don't want to create a bunch of new background ponies for that episode, but its still a bit odd to me, like when filly Twilight is standing next to a much older Lyra...