In the fight with the guys in the yellow Hummer, he is thrown in front of a silver car, and it looks as if he narrowly makes it out of the way. But when we see what is recorded on the camera, the car comes nowhere near him and he's already running back towards the other guys while the car is veering long before it would have even reached him.
When Jake goes to the gym after sticking up for Baja in the parking lot, he throws a kick to Roqua's head while he trains him, in which Roqua has to duck. Later in the movie, when he's training, it shows that he cannot kick that high.
The first time Jake ever goes to Roqua's gym, he spars with Miles. He throws a punch early in the match, and you can hear the breath he takes when throwing the punch. The next day, Jake learns that you should breathe out when you punch.
In the opening scene, the football commentator calls a third down, but the man holding the "stick" at the side of the pitch clearly shows a second down.
During the Beatdown, when Jake is facing Dak-Ho, right as Ho delivers a hard back kick in response to Jake's right cross, the camera clearly shows Dak-Ho's right foot kicking Jake's ribs. But, when the camera zooms out, it shows Dak-Ho just used his left foot for that last kick.
During the fight scene when Jake gets out of the car to fight the three guys in the Yellow Hummer, Max lifts up his video camera after Jake throws his first punch, but after the fight, when all of the students are watching the fight on the net at school, it shows that Max is recording before the fight even begins.
iPhones were used throughout the movie to record the fights. This movie was released in 2008, video capability for the iPhone wasn't available until Summer of 2009.
When Max tells Jake "The Beatdown is tomorrow night," his lips and his words do not match up.
When Jake arrives at Sean's gym on the first morning, there is daylight present. This would be at 5AM, since Sean told him to be there at 6AM and he shows up an hour early according to what Sean says. This is never possible for Orlando, Fl.
At the party at Ryan's house, Max exclaims that "Force times mass equals acceleration!" when the actual physics equation is: Mass times acceleration equals force.
When Roqua says he hasn't seen his family in seven years, he only holds up five fingers.