Other mistake: When we see the Dean's phone contacts, they're suppose to be in alphabetical order, but "Aisha" comes after "Andres" and before "Annie." It should be before "Andres." And "Albino?" is after "Freckles."
Other mistake: During Leonard's "Let's Potato Chips" YouTube video during the ending credits, you can see the video reaches the end of the load/play bar (watch the circle), yet the video continues for several seconds. Once the circle reaches the end of the load/play bar, the video is over and won't continue.
Other mistake: When Annie comes in and shoots the cheerleader squad, there are six cheerleaders in the squad. One of them starts bickering with Annie and Annie shoots her again in response. But if her gun only held 6 bullets, and she shot all of the other cheerleaders, where did the seventh come from? And she never picked up another gun or reloaded after she shot them.