These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Potter Puppet Pals
Ear Worm: Any one of the songs. The most infamous is "The Mysterious Ticking Noise".
Harry sang the most self-praising 'I Am' Song in "The Vortex."
Don't forget the Draco Malfoy song!
The birthday song from "Neville's Birthday" apparently proved so catchy, Neil released a video containing that song by itself.
For (even more) Hilarious in Hindsight: Dumbledore says at the end of Ron's Disease that he's a gay android. Guess what Rowling revealed later? (hint: not the android part).
Some of the entries in "Snape's Diary" are actually rather heartwrenching.
True Art Is Incomprehensible: "The Awakening of the Incorruptible" is almost Dada in its deconstruction of standard dramatic tropes, its rejection of the noise of modernism for the postmodern silence.