Did you know first Mickey Mouse cartoons were not done by Disney films.
Because “Disney Films” as such did not exist.
The first appearance of Mickey (and Minnie) Mouse was the silent short “Plane Crazy”, made by Disney Brothers Studio in 1928 and shown to a test audience, but did not get a distributor.
The first-to-be-released Mickey Mouse film (which also included Minnie) was produced by Walt Disney Studios and distributed by Celebrity Productions Cinephone in 1928. It was the first sound-on-film animated picture. Following the success of “Steamboat Willie”, “Plane Crazy” was given a soundtrack and distributed by Celebrity Productions in 1929.