What Should Have Been Done
Once they found Donna at the prom and got her in a car, they should have driven her far, far away to a secret location. NOT to her home, where every window seems to be open. Seriously, close and lock all the windows. If she must be at home the aunt and uncle should have AT LEAST stayed with her the whole time. I wouldn't have let that girl out of my sight. They probably should have taken the steak knives and all holed up in the basement or even a bathroom. You can't be too careful in this situation, where you know a killer is on the loose and hunting you.
When I watch a slasher, I know it's not going to all make sense, and I'm not really that smart so a lot of goofs get past me. I don't see goofs in movies that most people find glaringly obvious, so when one sticks out to me like this, it's bad. I enjoyed the movie, for the most part. I mean, yes, they were not the smartest teenagers, but nothing that they did really bothered me that much (EXCEPT for Donna's "Oh wait, I left my mother's shaw in the hotel room. I'm gonna go get it." Like, follow the police's orders. It's not that hard.) until the end where they pretty much just set up Donna & Co. for another attack.