SlashFilm:

Disney is a prolific company with its name on a great many successes, and it likes to hide its missteps and failures. The process of doing so sometimes helps those mistakes become things of legend. Song of the South, with its politically incorrect and racist portrayals of certain characters, is likely the most famous example. Another example might be The Sweatbox, a very rarely-seen documentary about the failed making of an animated film called Kingdom of the Sun, which eventually morphed into The Emperor’s New Groove.The Sweatbox filmmakers John-Paul Davidson and Trudie Styler were given unprecedented access to Disney’s process and the resulting film painted the executives in such a negative light, they more or less made sure the film would never been seen in public.

A harsh look at the process of making movies with some cool behind the scenes footage.