You've captured a very good sense of movement - I can just feel myself falling when I look at this! However as ~REV6Pilot said the rainbow falls could be interpreted as fabric if you look at the top. Overall it's great!
A liberal but still cute take on the show's shape style, vivid coloring, and lighting of a professional quality level. What's not to love? ... Actually, there is one thing: you drew so many parallel lines at the top of the rainbow waterfall, it looks like a piece of fabric instead of actual liquid. Make the top smoother, and make those lines curvy, and you're set on a fluid flow