Continuity mistake: When Jackie and the five men are fighting in the streets and Jackie's mother throws him two bottles, he breaks them on each other and he starts drinking. The first shot the bottles are broken when he is drinking. In the next shot when it changes from the head gangster and back to Jackie, the bottles aren't even broken. They are new bottles, with the lids removed. How can bottles repair themselves?
Revealing mistake: In the final battle between Jackie and the main villain's henchmen, the villain throws burning alcohol at Jackie. Jackie puts out the fire the first time. The second time this happens and Jackie is rolling to avoid the flames, you can see his left leg of his trousers is already burning even before the flaming alcohol reaches him.
Other mistake: When Fei Hung and his father return home near the beginning of the film, the father walks in the background with a servant. Fei Hung does something with the suit he is wearing. Look at what he is doing closely and you will see that he seems to be "unzipping" something. There isn't a zipper or anything for that matter where his hand is.