Trivia: In an attempt to manipulate the MPAA into giving the movie an R-rating, Wes Craven sent them a copy of the film that was far more violent than he actually wanted the movie to be. His idea was that when they demanded cuts so it wouldn't be NC-17, he could submit his actual director's cut with less violence, and they'd likely accept it. To his horror and amusement, they gave the far more violent version an R-rating. Regardless, he still released his less violent cut of the film in theaters.
Trivia: SPOILER: There's a "blink and you'll miss it" clue to one of the killer's identities. When they discover Randy's body, there's a quick shot of his bloody hand. Among the smears of blood, you can also very briefly see a distinct red lipstick mark on his hand. It's similar to the lipstick shade Debbie Salt wears in a few scenes. Debbie is later revealed to be one of the killers, and mentions that she killed Randy. (Presumably he got her lipstick on his hand while they were struggling).
Trivia: Gale's cameraman Joel leaving was actually an idea actor Duane Martin had. He pitched the idea to Wes Craven, saying that there's no way his character would actually stick around once the bodies started piling up. Craven asked him how he'd leave, and Martin replied that he'd "take a cab." Craven found this idea so funny that he actually worked it into the film, and also added the moment where Joel returns at the very end once the killers were dead.
Chosen answer: In real life, they'd have known there was a phone call involved. They would have known her boyfriend was killed. They could have easily pieced together that the killers played a cat and mouse game with the Drew Barrymore character. But that doesn't account for all the details. Anything else would be speculation. My speculation: Maybe Billy Loomis kept a diary.
K.C. Sierra
And rumor has it that Stu didn't die that he may still be alive.