Scenes that included Odd and Stormy's origins were cut from the film. One including young Stormy and her step-father and another including young Odd and his mother. Odd's mother put a gun to his head and is later taken away while cutting paper roses. DJ Shamus and most of Ozzy's scenes were also cut from the film.
In the novel, Thomas meets a young boy who shares his gift and actually gave him the name for the shadow creatures, "Bodachs". Shortly after saying the name the boy is killed by a runaway car pinning him against a wall. This is how the lead actor, Anton Yelchin, died in real life.
Several notable characters from the novel were cut from the film: Terri Stambaugh, owner of the Grille Odd works at, motherly figure, and a walking encyclopedia of Elvis knowledge; DJ Shamus, blind radio host (a sign can be seen advertising his radio station when Stormy and Odd first walk into Green Moon Bowling Alley); and the ghost of Elvis. Little Ozzie also had an important role in the novel, as he was the one who convinced Odd to write his story, but is only in one scene of the film.
The trivia item below may give away important plot points.
A number of clues are evident that confirms Stormy's death before it is revealed with dialogue. 1. Just very briefly you can see the bullet hole in her shirt as she rises up from the counter. Although later you see her shirt is far more bloodied and has more bullet holes, we have seen that the dead can alter the appearance of their clothing and state of health. 2. After the shooting, no one looks at or directly interacts with Stormy. 3. Just prior to the revelation, Odd is eating breakfast with Stormy, but while he has a full bowl of cereal and a glass of orange juice, her bowl and glass are clean and empty. 4. But the biggest clue is that she never says a single word, and it has been stated and shown throughout the movie that the dead never speak.