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.
Revealing mistake: When the Chosen One is fighting Betty in the river, Betty turns around and hits the Chosen One with his claw, sending him flying. In his flight, you can see the Chosen One's face is not a white man, but an oriental man. They have forgotten to paste Steve Oedekerk's face over the original character from the original film.
Revealing mistake: When Chosen One is fighting the masked attacker (who later turns put to be Betty) he claws out their eyes and starts screaming and then his vein in his neck bursts. When this happens though you can see a patch that is bigger than the skin on his neck and it wrinkles it out, revealing to be the blood patch.
Revealing mistake: When Chosen One and Ling are talking and Chosen One says/shouts, "I implore you to reconsider", look at his head as the camera zooms in. After the zoom stops, you can see that Chosen One's head "grows" for about a half-second, the result of a flub-up of the special effects. (His face is pasted onto another actor's body.).
Revealing mistake: During the scene where Betty is at the table with the Chosen One, when the camera is behind the Chosen One, you can see a mustache on him sticking out on the side. The Chosen One does not have a mustache. This also happens when Betty is performing his skill. This is where Steve Oedekerk is replacing Master Tang instead of the Chinese guy he usually does.