Visible crew/equipment: In the opening credits sequence, where Chosen One is driving a car and Master Tang as the narrator says "And sometimes he drove," you can see the faint reflection of the camera car filming. It's best to see on the tail of the car and just below the silver bar you can see the wheels of the camera car.
Revealing mistake: When Chosen One is training and Wimp Lo comes up to him and says: "Knock, Knock. Who's there?" You can see that he is transparent because the scenery is visible through him, this is easily seen in his black hair. It is also apparent when he says, "Take a close look 'coz I rule baby". But by the next shot he isn't transparent anymore.
Continuity mistake: When Chosen One is training to defeat Betty by practicing on wooden dummies, there's three shots of him hammering. In the first two the wooden Betty had lots of hair and a mouth, but in the third one, it has a little bit less hair and no mouth.