the first ever fully synchronize sound cartoon and walt disney mickey mouse make his screen debut in the exceptionally entertaining cartoon short subject steamboat willie . mickey be a worker on a steamboat under the supervision of captain peg leg pete ( or pete a he would later be call ) . mickey board his long time companion minnie mouse aboard the train a they frolic about and while mickey attempt to impress minnie . this short be wildly fun and positively entertaining . animator ubbe iwerks and rudolph ising and and hugh harman assist walt on the creation of the short . steamboat willie essentially mark the beginning of the success of the walt disney company .