Revealing mistake: When Tommy Ross gets killed and Carrie looks at his supposedly lifeless body if you look closely you will notice he blinks revealing that he is actually alive.
Revealing mistake: During the prom sequence, when the moon-shaped light fixture falls onto the stage supposedly "setting the stage on fire", you can see that it is a fuel line that is starting/controlling the fire.
Chosen answer: It is an implication that Carrie White is not really dead.
BaconIsMyBFF