Just at the beginning of the first street fight drunken boxing scene, Fei-hung's Step-Mother pushes past a tall blond man in a grey suit and tie to go inside with her girlfriends and get Fei-hung some wine. In the next scene, we see them go up to the bar and grab some bottles, first pushing past the exact same blond man from outside.
After being set on fire by Fei-hung, foreman Henry is played by director Chia-Liang Liu in disguise.
The burns Fei-Hung receives to his hands and face in the final battle when he falls into the hot coals disappear right before he drinks.
When Fei-Hung gets pushed into the pit of fiery coals, his clothes get singed and filthy. As he gets out of the pit and tumbles down some stairs, his clothing is perfectly intact. When we see him at the bottom of the stairs, his clothes are tattered and dirty again.
When John is kicked into the pile of coals, the gloves on Wong's hands can be seen briefly just before he (and John) reach the other side.
When Fei-Hung's mother offers something to the customer who ordered the ginseng his father says "What are you doing with that rutabaga?". That was not a rutabaga. It was in-fact a daikon radish. A type of white radish used in Asian cooking.
About 4 minutes into the movie when Jackie Chan's character is playing chess with his father on the train, and trying to distract him to look out the window, his father doesn't look: if you look, you will see a large airplane flying past just after the trees go by.
During the fight with the mob, one of the axe-wielding thugs can be seen brandishing a crowbar.