Revealing mistake: When Roy and Chon arrives in London you can see ships on the river Thames. However the sails on the ship are to tall for the ships to be able to get under the bridges. (00:21:45)
Revealing mistake: During the "Singing in the Rain" segment of the big fight after Chon and Roy arrive in London, watch carefully when Chon "lifts" himself with one arm, raising his legs to the side to dodge a strike. It's clear that wires were used, as his body somewhat unnaturally lifts up. (00:31:15)
Revealing mistake: It is really obvious Jackie Chan was on a wire when holding onto Roy at the end. His body floats and moves in a very unnatural way.
Revealing mistake: When Owen catches Jackie at the end, you can see Jackie Chan hitting the "glass" of Big-Ben, which bends like a painting or other set prop. This happens very quickly.
Revealing mistake: During the final sword-fight, in at least two shots, when the camera is facing Chon Wang and Rathbone's back is towards camera, you can tell that Rathbone is being played by an Asian stunt-person for certain moments. His hair doesn't match perfectly, his body type is SLIGHTLY different and you can even occasionally catch very brief glimpses of the stuntman's face in shots where he twirls around. (Most noticeable early on in the fight during the stunt where Chon jumps up onto the railings after blocking and dodging several swipes from Rathbone).
Revealing mistake: When Chon Wang and Fann Wong are fighting on the barge, Chon uses a life ring to block an attack from the wooden stick and it flexes like rubber, later in the scene the stick appears wooden.
Answer: The song is "My Generation" performed by The Who.
moviemogul