Divorced Installment: Kevin Williamson wrote a script for Scream 3 that was never used, focusing on a "fan club" for the Woodsboro killers and the Stab movies seeking to become famous. Years later, he dusted off his old idea, removed all references to Scream, and created the TV show The Following.
It isn't much of a stretch to imagine how NancyDrew could hatch a murder scheme, given that she's solved several over the course of her career. But who ever imagined that the kid from Signs would be the accomplice?
Curiously enough (or not), most of the Japanese voice cast voice their respective expies in the Japanese dub of Scary Movie, especially Michiko Neya dubbing the heroine of both films.
Irony: The prop for Ghostface's knife was based on the Buck 120 hunting knife, which was chosen because it had a very long blade that looked scary on the screen. In real life, this knife was discontinued because the blade was so long that it made it difficult to gut animals... that is, the one thing that knife is most famous for in the movies.
Also, in Jay and Silent Bob Strike Back, the duo stumbles upon the the filming of a Scream movie. The first movie in the series had a poster for Clerks, a movie in the same continuity as Jay and Silent Bob. That said, it's not explicitly stated to be a Scream film; some fans believe it could have been a Stab movie. Jay and Silent Bob themselves show up in a blink-and-you-miss it scene in Scream 3.