 SPOILER: In the DVD Documentary, Bill Phillips (I) (qv) says that  he cut out the novels plot line of the dead owners spirit  possessing Arnie and actually causing Christine to kill not only to  save time and compress the story, but also because he didnt want it  to look like they were copying  _An American Werewolf In London (1981)_ (qv) where Jack does the  same thing to David.