The setting of Needful Things is a fictional town called Castle Rock, Maine - as in Stephen King's novel. The distribution company Castle Rock was named after it when it released Stand by Me (1986). Castle Rock was also the setting for The Dead Zone (1983), Cujo (1983), and The Dark Half (1993).
Brian Rusk's mother appears in the longer, 3 hours version. In her sidestory she purchases sun glasses worn by Elvis Presley. She can still be seen in the cut version of the movie at the end wearing the sun glasses.
In the film, Hugh Priest buys Gaunt a football jacket while, in the novel, he buys a fox's tail just like the one he used to fix to the car's aerial. If you look closely, the tail is visible during the flashback scene, just when Hugh tries the jacket in the store.