Plot hole: George Lebay says that his brother died "6 weeks ago" inside Christine and that's why he's selling it. Later that evening after Arnie leaves his house and goes to Darnell's, Will Darnell says he "knew a guy who owned a car like that" and "the bastard killed himself in it." If it's only been 6 weeks since his death, shouldn't Darnell have recognized the car? It's not like there were lots of red Plymouth Furies (custom order color) running around the small town, let alone the USA, even in 1978. (Also considering how production even had a hard time finding them for the movie).
Plot hole: The police let Norman back to his house on the same night multiple murders happened. He is even allowed into the fruit cellar, where most of them happened. (01:38:25)