Other mistake: At the beginning of the movie it states that the documentary crew went to Mount Rose in 1995 for its fiftieth anniversary. Yet when the crew is interviewing Amber, after her costume is stolen, the graffiti on the wall next to her has the dates 1996 and 1997.
Factual error: When Gladys Leeman and her cohorts pull up to the Mall Of America in the beginning of the film. The documentary crew talks to Gladys in the parking lot. If you look carefully, you can see a Target store in the background. This scene was not filmed at the Mall Of America, mainly because there is no Target anywhere near the Mall Of America.
Deliberate mistake: Rebecca's 30-06 has no scope and no open sights. So having gotten it for her birthday several years earlier, it's still pretty unprepared to fire.
Continuity mistake: In the scene where Amber first realizes her tap costume is missing, the scene starts with Lesley Miller walking by in a white bra and red panties. In the very next shot, she is sitting doing her makeup in her physical fitness costume.