Koko the Clown, the protagonist of Out of the Inkwell, had been a secondary character in the movie shorts of the 30s starring Betty Boop. The singing voice of Koko back then was provided by Cab Galloway.
The Fleischer brothers, Max and Dave, had been experimenting with animation and Out of the Inkwell some years before the 1920s. They founded Inkwell Studios in 1927. One important competitor of their animation was a young man named Walt Disney.