* The {{Animesque}} ImagineSpot.
-->'''Flower''': Horton's the greatest hero of them all! HAAAH!
** "[[EpicFail But Mount Nool is that way!]]
** "I will make monkeys of these monkeys, for it is their destiny!"
* Vlad choking on a clover. "Holy moly!"
* The entire breakfast sequence, including Sally's motherly but offhanded "''That's'' one of my girls!"
** One that appeared often in the trailers; Ned tries to get a word out of Jojo...by using his interpretation of teen slang. Vow of silence or not, can you really blame [[OnlySaneMan Jojo]] for not wanting to dignify [[EpicFail that]] with a response?
* The portraits of the various ancestors... including the "... not-so-great" grandfather.
* '''THE ANIMATION.''' Never before have CG characters squashed-and-stretched so much as in this film and the animators utilized it to great effect, eliminating any doubt that CG models can move just like hand-drawn characters!
* The business with the two Vlads- the bad Vlad... and the bunny Vlad that makes the cookieks!
** [[SarcasmMode "Yeah, Horton. She's sending you a bunny with cookies."]]
* "How could he call me a boob? I would never call anyone a boob. [[HypocriticalHumor HE'S the boob!]]"
** Later, Horton gets the chance to threateningly call the Chairman a boob, scaring him a bit before [[ItAmusedMe telling him he was just joking]]. You could tell from the Mayor's smile that he was quite satisfied.
* The scene in the Town Hall where the Mayor thinks that maybe they should cancel the Who-Centennial. The Councilman presses a smiley button, a dome descends around the Mayor and the council, and Muzak begins playing, causing the panicked Whos to relax. As this is happening, the Councilman is chasing the Mayor around the dome. In the next shot, he's strangling the Mayor. And then the next shot shows him pointing first to the Mayor and then to a picture of a donkey. [[GettingCrapPastTheRadar Probably not too hard to guess what the Councilman was calling the mayor.]]
* "Oookay, Hor-ton - ''fake name'' - where are you?"
** "Oh, voice from the drainpipe."
* The first time you see Ned the Mayor. He's stirring his coffee, then he bends to pick up his newspaper and spills it all without noticing. He then goes to take a sip and looks adorably confused as to where his coffee has gone.
** The deleted scenes show that the scene would have been extended. Ned finds his coffee landed into the wheelbarrow of a garden gnome, and tries to drink the coffee from out of it, getting him stares from his neighbor.
* "I don't even remember. Yes, I do. BLAAAARGH - you know, some guy was talking to me... ''not'' an elephant in the sky. A guy on the ground."
* Jojo's [[FunnyBackgroundEvent utter]] [[AudienceSurrogate confusion]] at the SuddenMusicalEnding, then eventually [[AsideGlance shrugging to the audience]] and joining in.
** The SuddenMusicalEnding itself.
* "No! This is not fun! This is a sign of doom! Everyone stop having fun, immediately!"
* Anytime Katie is onscreen. Although it's honestly equal parts funny and equal parts... incredibly creepy.
** Katie puts her clover on her head, gets on her hind legs, and disappears backwards into the brush. It's both hilarious and, frankly, a little off-putting.
** It might be mean-spirited but Sour Kangaroo [[HypocriticalHumor kicking her across the jungle]], straight over a tree that resembles a field goal.
-->'''Tommy''': ''It's good!''
* entire Horton Crossing the bridge scene.
-->'''Horton''': I just need to think light. I'm light as a feather. I'm light as a feather!\\
[feather floats gracefully down on to bridge plank...then ''the plank gives way''\\
'''Horton''': Heavy feather...
** While Horton is crossing the bridge, meanwhile the Mayor is visiting the dentist, already feeling a bit nervous. Every small earthquake (resulting in such things as dental rinsing water being poured into his ''eye'', and the Novocaine needle jabbing his ''arm'') the dentist is ''utterly nonchalant'' about it.
* The mayor glares at the councilman's portrait
-->'''Mayor''': Look at you...yuck! look at your face. And I bet you don't look so good with a STAPLER IN YOUR HEAD!\\
[throws stapler which bounces and staples the Mayor on the forehead]\\
'''Mayor''': YEEOWWWW!!!!!
** His assistant Miss yelp then removes the staple from his forehead ''barely even looking in his direction'' like it's happened before
-->'''Mayor''': YAH! thank you, Ms. Yelp.\\
'''Ms. Yelp''': You're welcome.
** Later during the Vlad chase, the Mayor rolls out onto his balcony, hits one of the railing pillars between his legs, then is shoved in further by his desk, a couch and a refrigerator... And just when things can't get any more painful, ''the stapler staples his forehead again'' and he screams.