Minuette dances back in time (and space!) due to a mathematical anomaly derived from Pinkie Pie's non-Euclidmare-ian geomaretry. Dr. Hooves* exploits the situation. Derpy challenges the Doctor. And Lyra Heartstrings finds a friend.
Happy Pi day! And one year since my registration here.
Era: Season 3 (the start of).
*Intentionally spelled as Dr. Hooves instead of "Whooves".
Image: The pie part of the image is by Lorc. The link details rights for the image only.