Jason was originally going to have Blue and Pink sing the Candy Mountain Cave song, but he couldn't sing really fast in a high-pitched voice, so he got the idea of having the letters from the Candy Mountain sign sing instead. He sang the song in a normal voice, then pitched it up.
After the success of the original video, [adult swim] contacted Jason about producing a Charlie the Unicorn TV show. Jason tried to retool the concept into a half-hour program, but only got as far as a network pitch before realizing he wasn't happy with the results and ultimately wound up declining their offer. In his own words, "there could have been a Charlie show, but it would have been a bad Charlie show". He did, however, release the pitch on the "Film Cow Master Collection" DVD.