When Jet Li is chasing the gang who steal his bag, just before he slides down the hanging material in the car park his hat disappears.
Johnny and Jet fall through a window at the very top floor of the building, yet when they jump out of the window, they seem to be several floors down.
Near the beginning of the movie, when the muscular man has been treated and is receiving pills, you can clearly see the hand of somebody pushing him sideways to stand better in the shot.
Near the end of the movie, when Johnny and Jet are hanging from the outside of the building, there are several cut scenes (especially the one where Johnny falls) where you can clearly see the soft padded mats and stagehands that will assist them in the fall.
In the scene where Johnny and Jet fall through the roof of the building into some sort of attic, you can see the blue padded mats that they are supposed to land on before the scene cuts and you see them landing on hard concrete.
At the end of the movie, when Uncle Tak gets to the top of the NRB building, the camera zooms in on Jonny, then zooms out, at this point, the track that the camera is rolling on can be seen.
When May and her boss are in the office, you can see the boom mic in the reflection of the window at the very top.