Pinking was created with a set made entirely of light (some scenes have more than 40 lights), and it was heavily dependent upon the location of the camera at any given moment.

This is what it looked like with the house lights on, plus some explanations added for fun. If you're interested in animating, maybe this will help you understand the process a bit better.

A bit of added detail on why I have the characters blocked in the way they are: as this was a dream, I wanted to cause a skewed sense of scale. By manipulating where characters were related to the floor, but not showing that specifically very often, it creates a surreal sense of how big everything is. Giant celestia is a great example of that. Without a frame of reference for how big she is, she seems almost infinitely large when set that way.