Still: Pete berates Mickey. Behind Pete's back, Mickey blows a disrespectful raspberry at him. Pete turns around, and Mickey makes a little fanning motion with both hands down by his bottom, as if to try to convince Pete that the raspberry was actually just an accidental fart.
I have never heard any mention made of this anywhere, whatsoever. It's subtle, but once you notice it, it seems unmistakably obvious and intentional.
There's a fart gag in Steamboat Willie. Sorry. But someone had to say it.