The military style detention in the first adaptation.
From that same movie, Tommy and his friends are out buying tuxedos, one of them briefly argues that none of them look good on him. The movie then fast forwards through their argument, until the friend settles for a tuxedo t-shirt.
Carrie herself has a funny Mood Whiplash moment when she accidentally breaks the mirror with her telekinesis.
Margaret: Carrie what are you doing up there?
Carrie: Just saying my prayers mama.
The fact that Norma always wears her cute little hat... Even when she's under a drying hood.
In the 2002 version, the principal quiets everyone down by simply shouting "SHUT UP!!!"
In 2013 film, the principal has visible problem with using words such as "period" and "tampons". While talking to Chris father, he says the girls were throwing "those things" at Carrie.
In the 2013 remake, Margaret literally thumps Carrie with the bible.
In the musical, the song "A Night We'll Never Forget" has this gem:
All Boys: Eighty bucks for tux! Damn, we'd better be laid.
Girl: You've been prayin' for that since seventh grade!