Near the end of the first film, Billy stabs Stu to make it smooth, like they were both victims. However, instead of just superficial wounds, the latter gets seriously wounded. That might be just an indication of Billy's unstable mental state, or... Maybe he judged the severity of wounds based on what he had seen in a number of slasher films, where people have a bad tendency of surviving wounds that would be lethal in reality.
Or, alternatively, he was always planning on screwing Stu over and being the sole survivor.
The fact the Stab movies are so popular is an illustration of how sick the culture is in the Scream world. They're, essentially, true crime slasher movies. An illustration of the cultural sickness may be how all of the students wanted to see their Principal's horrifically maimed body.
What may be obvious to some but struck me was the reason movie tropes are so important is that everyone is indirectly or directly tied to film somehow but Billy and his mom. Most of the killers want to be touched by fame so they go to an obvious but psychotic source. Likewise, many of the people around the killers are fame obsessed themselves.
Ghostface, no matter the identity, is a terrible killer. His victims are constantly kicking him and damn near getting away. Who is the one person Ghostface kills nice and smooth, no muss, no fuss? Billy, in Scream 1. Hint to the viewer that his death isn't what it appears.
In Scream 4 after Jill is revealed to be one of the killers, she goes through a lot of trouble to pull off a Wounded Gazelle Gambit. It makes you feel a tad bit sorry for her that the whole thing would go bust, and probably sooner rather than later, given that she grabbed the Idiot Ball immediately before she started kicking the crap out of herself. Her newfound fame would have vanished and she'd of likely ended up in jail or institutionalized if she was lucky. Anyone who watches Lifetime (and certainly a detective or forensics expert) knows that shooting a man in the groin is not a defense wound. It's a revenge wound. Gazelle Gambit fail.
Of course, she probably could have passed it off as a wound Charlie inflicted, claiming that the two had both been the killer and that Charlie double-crossed Trevor, being jealous of Trevor's relationship with Jill. She did think pretty much everything else through, after all.
At first it seems strange that Ghostface doesn't kill Gale, even though he had a chance, instead choosing to wound her. It makes a lot more sense once you realize that Jill not only wants to steal Sidney's "celebrity victim" fame, but also her friends.
The supposed Ending Fatigue in 4. They discuss how the original ending in the first film will be the false ending in this one. They say that the party is the false ending. However the original film's ending was the house, therefore the house is the false ending in 4. Thus the extra bit at the hospital.
Billy's callous disregard for Maureen's death, evidenced by him telling Sidney (her daughter) that she should just "get over it already" makes perfect sense considering that he's the one who killed her.
As noted above, Ghostface is a lot worse at killing people than other slashers. Why is this? Because the Scream series is a Deconstruction of Slasher films! The victims are not Too Dumb to Live, unlike other slasher victims.