And, strangely, both elemental episodes have had an Alicorn in the background. The security pony flying around in Manehatten and a yellow and green mare today. Wonder if that's somewhat deliberate.
Interesting observation. People on derpiboo.ru have been tagging them as "animation error," but I wonder. I'd figured maybe they were doing it to make Twilight seem less unusual, what with her walking around openly and nobody noticing or caring that she's got wings and