Character mistake: At the Roadhouse Cooper states that the second victim (Maddy) was found dead two days ago. It has been less than 24 hours since the body was found: he likely means she was murdered two days ago.
Character mistake: When David encourages the gang to dance at Scott's birthday party, David mistakenly calls Kelly by her actress' name, Jennie Garth. He says, "Scott, you're off, Buddy. Jen, kind of getting into it."