When Whittier is giving her speech to the new squad, her note cards change from lime green to hot pink.
At the end of the film, the Stingers come out to do their routine and get in position on the stage. Then the mascot comes out and the Stingers have vanished. When the mascot has finished, they are suddenly back.
In the end scene where the judges are passing a sheet of paper down the table to the Dean, the paper is folded in half and has some kind of printing on the back, but when he gets on stage he has a piece of notebook paper folded in quarters
In the scene during the showdown, when the renegades are looking down the ramp, they switch camera angles and show the stage and the backdrop has the renegade logo, then they switch angles on the stage and it's the Varsity logo. It happens once more several shots later.
The writing of "Better" on the board changes between shots.
In the scene where the cheerleaders do their first performance at a game in front of the school, some of the cheerleaders have earrings and necklaces on. In real cheerleading, it's against the rules to have any form of jewelry on.
During the softball game it shows the infield filled with grass. Softball infields are all dirt unlike the field in the movie.
The fencing team members are fencing with sabers, but they're wearing lamé vests for foil. Saber fencers would be wearing lamé jackets that cover the arms and the head, and do not cover the groin.
In many scenes after Marni gets a black eye (mostly during the Varsity performance) you can see that her eye is normal, but in the next shot the black eye is back.
During the audition, when the stunt double performs Whittier's back handsprings, Whittier doesn't land in the same position as the stunt double.
A yellow tape marker can be seen under Derek, when he and Whittier are in the pool at night.
When Marnie starts to explain why the other team doesn't exist, she says that it's according to the 'section 8' of the bylaws, but she raises 7 fingers. It might as well be deliberate mistake to show character's dumbness.