Oswald's "tough guy" stance while he's trying to get Mickey to fight him. An adorable, scrawny rabbit attempting to look muscular was enough to take a rather dramatic moment straight into Narm territory.
Pete Pan, he's just such a big walking (well flying) Crowning Moment of Funny, basically a version of Pete prancing around happily in Peter Pan attire, it gets especially hilarious if you choose to save the sprite and he comes in to fight the animatronic Captain Hook, it has to be one of the most bizarrely funny moments in the game.
The scene where Mickey and Oswald fix their relationship near the end of the game basically starts out as a Crowning Moment Of Heart Warming, but then takes a comical twist as the two are about to shake hands, Oswald pulling his away.
In the Graphic Novel, Mickey gives a really cheesy Badass Boast speech to one of the bad guys: "You know it! Everyone knows it! You don't mess with the mouse!" Five minutes later, Oswald comes in to give his own speech, and we find out just how much they resemble each other:
"You know it! Everyone knows it! You don't muckwith theLUCK!"
Very Blink And You'll Miss It, but when Mickey first wakes up in Dark Beauty Castle, he VERY briefly pulls a face that can only be described as Oh Crap or "O_o".
In the Graphic novel the Rocket scene gets an added bonus. As the Rocket's going down due to the paint drained out of it Mickey can be seen writing something.
Mickey: I, Mickey Mouse, being of sound mind and body...
Possibly unintentional, but Mickey's reaction to the Mad Doctor's name in the novelization.
Mickey's Thoughts: This guys wasn't just insane, he was proud of it!
There's something hilarious about the idea that Oswald named all 420 kids after himself. Girls included.
If you place a TV (which plays Mickey's Steamboat Willie cartoon) in front of Oswald, he will turn away from it defiantly only to give into temptation a few seconds later and stare at the screen, completely mesmerized by the cartoon.
Some of the comments characters give after being saved from the Bloticles, some of which are surprisingly nonchalant and distracted.
Generic Dog: Next time, I'll hide in Clarabelle's house. It smells like pie.