When Liz is getting chased she is wearing a jacket, but in the next shot she is not, but then in the next it appears again.
In the opening scene where it is 1989 New Jersey. You can see a Ford pickup truck model from the years 1997-2003
While in the van Cathy and Liz are texting each other, when Liz reads her text message you can see the cursor meaning she wrote the text message, she didn't recieve it.
When Jen is first picked up she is wearing a bikini top, but when she does the topless scene she only unbuttons her shirt. There was no bikini underneath.
In the beginning of the film a number of newspaper headlines are shown including one that reads "Killer Sentenced to Life in Mental Institution." Yet later in the film Jim says that he read an article about the event that said that the killer had died. Bill then reveals that the media had reported that the killer had been killed, and the fact that he was locked up in a mental institution was a secret known only to people involved in the case.
When they pull away from the college to begin their road trip, there is a suitcase left in the street that you can see as the car speeds off.