Revealing mistake: At the start of the movie, when the axe gang leader is finishing off the now-one-legged man, you can see in his shadow that he's not hitting the man. Also, if he did hit, you should think that he'd have to pull out the axe blade again, but again in the shadow's arm movement, you see him move his arm in a circular movement, not hitting the victim.
Kung Fu Hustle (2004)
1 revealing mistake - chronological order
Directed by: Stephen Chow
Starring: Stephen Chow, Qiu Yuen, Shengyi Huang, Wah Yuen, Xiaogang Feng, Zhihua Dong
Continuity mistake: In the last scene where Sing is fighting the Beast, Sing does the "Palm Move" on him. In one shot there's a close up of Beast with the hole of Sing's hand print in the building to his left, in the next shot Sings' hand is actually to the Beasts' right.
The Beast: All I want is to kill you, or be killed by you.
Trivia: Foreshadow: There's bunch of frogs/toads outside the Beasts' cell, later in the film he fights "Toad Style."