No pun intended - the past should stay exactly there. In the past - do not bring it up ... well or do bring it up .. just be sure you'll be able to handle the mayhem that it can cause. Steamboat Willy is known for being an early entry for Mickey Mouse - for the longest time even thought to be the first depiction of Mickey Mouse entirely. On film that is, of course.
That aside though (seems like there was a mute short before that, called Plane Crazy), Mickey and his friends want to rewatch this (which I reckon makes it breaking the fourth wall .. a it does break walls a lot). We do not get to see the whole short - we get to see a few scenes from it - nothing too controversial. But the old Mickey breaks out - and while it may look and feel like a lot of fun ... it goes south and wrong quite quickly.
This actually has to change its ... tune! To combat the past and be able to secure the future ... all in the can (yes I know - puns galore). But don't we always want more? More Mickey more Disney? Be careful what we wish for I reckon ....