Heartwarming / South Park: Bigger, Longer & Uncut
Kenny wishing to reverse everything that happened, giving up his chance at being brought back to life.
"Goodbye, you guys."
Later on, we're given a sweet scene of him shooting up into Heaven.
Stan and Wendy making up at the end.
Sheila apologizing to Kyle at the end.
Plus, when Kyle reminds her that it was Cartman's "fucking filthy mouth" that saved them, she didn't go nuts like she would have.
Sharon and the other mothers quitting the M.A.C. to help their kids. Doubles as a Moment of Awesome.
Kenny's conversation with Satan.
La Resistance gathering around Terrence and Phillip to stop the military and Kyle's mom from executing them. Also counts as a Crowning Moment of Awesome for Kyle for standing up to his mom. Unfortunately, she doesn't listen.
Terrence and Phillip appear be to quite taken aback by the gesture themselves.
Kyle: I don't want a fighter, I want my mom.
Sheila patting Terrence and Phillip on the shoulder during the reprise of "Mountain Town" at the end.
The Mother's: ( singing) Cause Terrance are Philip are sweet.
Sheila: ( hugs the brothers) Super Sweet!
When Kyle hides Ike in his attic, he makes a promise to Ike to stop all the madness, get their mom to come home and become a happy family again.
Kyle's Armor-Piercing Question to his mother, reminding her that her own adopted son is Canadian. This and the above moment each show that Kyle does care about Ike in spite of how he treated him at the beginning of the movie.
A blink and you'll miss it one, during the La Resistance musical number, Kenny's dad has a picture of him on his helmet.
"Through the Eyes of a Child", the last end credits song. It pulls off the seemingly impossible feat of being a tongue-in-cheek Award Bait Song parody that retains the wit of South Park while still having a poignant melody and lyrics (about the innocence of children, or lack thereof).