Karla Wilson: "Try" is like "maybe," Julie. "Try" is bullshit.
Nancy: This island didn't have a murder rate until you people showed up.
Tyrell: Don't get her started all right. It's a long fucked up story and you probably won't believe it anyway. All I know is that this is the worst vacation of my life. I'm tired, I'm hungry, I'm fucking horny and I ain't seen one goddamn psycho killer.
Answer: I believe it was supposed to be a surprise plot twist, I don't remember there being any indication that Will was setting them up.