I've never understood why it's a Crystal Empire when it seems to be just a city.

Pinkie in a Fluttershy costume 

It's weird that when ponies wear a helmet their hair sticks through the top. That's not how a Roman helmet(called a galea) works.

In this episode and the wedding episode we saw Cadence glide but not actually fly. For a long time I thought she was handicapped. It would have been interesting if she showed up in a Scootaloo episode to make her feel better. But Cadence did fly later on.

Apparently the point of Celestia's test was for Twilight to put the mission ahead of her own ambition. They could have made that more clear. Anyway this is MLP. It's always about depending on your friends.