Other mistake: At the beginning of the movie, Brit's parents announce that her father has lost his job, but only a few seconds later he says that the company is relocating to Crenshaw Heights. If he has lost his job, there would be no reason to follow the company to Crenshaw Heights.
Revealing mistake: At the end of the movie when the cheer squad is shooting the video with Rhianna, she is wearing a blue shirt. The shots cut back and forth between the reality of them shooting the video in front of a blue screen and what the video looks like with the effects. If Rhianna is wearing a blue shirt and is filming this on a blue screen, she would appear to have no body when no one is behind her.