Because Chloë Grace Moretz was a minor, she was limited to 8 hours of work per day. Many of Julianne Moore's scenes where she was interacting with Moretz's character (who was not in frame) were shot with director Kimberly Peirce subbing for Moretz.
It was an especially hot day with temperatures lingering around 103 degrees when they shot the scene in which the girls exercise on the football field, and director Kimberly Peirce worried that the cast was going to collapse from the heat.
There's one detail of the prom scene in the book that's not present in any of the films: Carrie actually stumbles off the stage and flees outside before she begins tearing the school apart with her powers, which she does by watching everyone through the window. For obvious reasons, all the films' makers chose to have Carrie standing on the stage above her classmates when she began attacking everyone in the room.
Originally the film was slated to begin with a scene from the book, in which a young Carrie wandered into the yard next door and found her teenage neighbor sunbathing. Margaret flies out of their home in a rage and scoops up Carrie, who throws a tantrum and summons a rain of stones. This prologue was also shot for Carrie (1976) and wound up being deleted from both versions.
In the pig farm scene, Billy Nolan (played by Alex Russell) kisses the sledgehammer before killing the pig. Alex Russell actually got sick after this because there were pig droppings on the sledgehammer.
In the novel, Margaret listens to the Tennessee Ernie Ford song "Let the Lower Lights Be Burning." Director Kimberly Peirce always planned to use the song, but when she discovered Julianne Moore could sing, she also had her croon the hymn. Moore's rendition was both in the film and prominently featured in the ad campaign.
Production was running over schedule and they were faced with abandoning the scene in which Carrie goes into a shop and finds fabric for her prom dress, but director Kimberly Peirce was adamant that it be filmed. The scene was shot quickly from one angle with no additional coverage.
The characters Heather, Nicki and Lizzy are loosely based on Helen Shyres and The Wilson Sisters. Characters from Carrie (1976) and the novel. That is why fans gave them the surnames: Heather Shyres, Nicki Wilson and Lizzy Wilson.
The trivia items below may give away important plot points.
Although it was a minor sub-plot in the book (it is mentioned twice), this is the first Carrie film to mention the possibility of Sue being pregnant. The marked difference, however, is that in the film Sue actually is pregnant and Carrie can even tell her the sex. In the original novel, however, Sue only suspected she was and this was proven wrong when she finally had her period, startlingly, right at the end of the book after seeing Carrie die, thus outlining the symbolic theme of blood that King had throughout his story.
In the original novel, Carrie and Sue speak to each other again after the disastrous prom in a powerful scene, in which Sue convinces Carrie she wished her no harm and holds her while she dies. This event doesn't play out, however, exactly like the book in any of the film versions: in the original 1976 film, Sue and Carrie never speak again and Sue goes into a mental breakdown after returning home, which is described in the sequel, "The Rage." In the 2002 version, Sue actually saves Carrie from drowning in her tub, drives her to another state and coolly pretends she never saw her after returning to town. And in this version, Sue finds Carrie in her house with her dead mother and Carrie faces her aggressively, lifting her off the ground and then finding by use of her power that Sue's pregnant. After exchanging some words and persuading Carrie she didn't mean to hurt her, Carrie flings Sue out of the house before it crumbles to the ground, and Sue goes on to testify in defense of Carrie's character in court.
When using her telekinetic powers during the climax, Carrie aggressively moves her arms, uses hand gestures, as well as displays enraged facial reactions as a command to her powers which is in stark contrast to Carrie (1976) and Carrie (2002) where she simply stands stoic as if in a trance while using the power.
Wanting to end the movie with a big scare and not to repeat the grave moment from the original movie, Kimberly Pierce was inspired by Lars Von Trier's Regit (1994) to shoot a scene where a character is giving birth and things go wrong. According to Pierce, the executives were really nervous about that moment because they wanted to avoid showing a vagina as much as they could. Finally, Pierce shot the scene but it didn't end up on the movie, only as an bonus feature on the Blu-Ray edition.
The scene where Tina is set on fire, the stunt double was really set on fire. Kimberly Pierce explains in the special features that she tried other methods but did not look correct. Her stunt double team had a gel that she covered the stunt double with and it helped her not getting injured.
The only version that gives Chris Hargensen a real death scene separate from her boyfriend Billy Nolan. In all three versions, they die in the car but in this version, Billy dies first by smashing his face into the steering wheel whereas Carrie lifts the car and sends Chris through the windshield face first into the gas station, which she then blows up.