Mrs. Desjardin, or Ms. Collins slapping the shit out of Chris was pretty awesome, considering how much of a bitch she is.
Even better, in the 1976 film, Chris tries to get people to side with her, but they don't even care, as proved when Sue tells her to shut up. It shows that Chris herself wasn't as popular as she thought she was.
Special mention to the school officials in the 2002 remake (and the original novel) who not only ensure Chris is punished for her actions, but also deliver a legal slap to her father's face when he actually attempts to sue them for suspending his daughter by threatening to file a countersuit on behalf of Carrie. The school official also makes special mention of Chris's numerous cases of harassing students.
Special mention goes to the Principal. Sure, he doesn't say Carrie's name right, but he stands up for her anyway.
There's also the 2013 version, where Miss Desjardin shuts the lawsuit threat right down by showing her father the YouTube video that Chris put up of the prank.
In the 1976 film, Carrie showing her powers to her abusive bitch mother for the first time. "Things are gonna change around here..."
The prom scene on the whole, despite being Nightmare Fuel for most, is pretty great to watch, but especially the way it's amped up in the 2013 film. Special mention includes Carrie causing Tina's dress to catch fire, not long after she posted the locker room video for the whole class to see.
In the 2013 film when Tommy calls the English teacher an asshole for being rude to Carrie.
Chris and Billy getting their comeuppance in the 2013 remake.