* AdaptationDisplacement: More people know the movie than the play or the book.
* AlternativeCharacterInterpretation: The film pushes the question whether Rhoda's sociopathy is influenced by her serial killer grandmother's genes or from being spoiled rotten all her life, though more likely it's a combination of ''both''; her genes may have not affected her so much had she not been spoiled and led to believe she should have anything that she wants. Christine, after all, has those same genetics and turned out fine, relatively.
* CompleteMonster: Rhoda kills a classmate to get a medal he'd won, had earlier killed an old woman by "accidentally" bumping into her on the ice, sets a suspicious caretaker on fire and plots to kill a friendly neighbor to get her pet lovebirds.
* [[HesJustHiding She's Just Hiding]]: We never do see Rhoda's body after the lightning strikes the pier.
* TheWoobie: Christine, and especially Mrs. Daigle, who only has vague suspicions about what really happened to her son that no one takes seriously.