Revealing mistake: During the dancing scene, Jamal shows the percussionist how to use the tambourine first, then tells him to start drumming, so he puts the tambourine down. However when he cues in the guitar, the tambourine starts to play again with the drums and guitar. A few shots later, with the tambourine still playing in the background, you can see the percussionist's tambourine sitting on the table next to him where he had left it.
Revealing mistake: In the final battle scene, Jamal is hitting one of the soldiers with his leg. As the soldier falls, it's clear that he throws himself back intentionally.