While fighting in the streets of Rotterdam, Jackie manages to lose both his shoes. He dons a pair of clogs to finish the fight and run away in, but for the rest of the movie he is wearing the original shoes again. In the Hong Kong version, there is a scene explaining this.
After flipping the car onto its side and scraping along the ground, the car Jackie and the two women are in is immediately shown without any scratches on either side.
When Jackie runs away after getting the computer disk, his clothes change back to those he was wearing before he changed into the company uniform.
During the car chase, Christine's handcuff, which is attached to the handle in the car, becomes undone when the car lands sideways. In the next shot it is locked together again.
When Jackie fights South African Police officials, he is hand-cuffed. But, in between, when he hits an office his hands are untied and in the very next scene his hands are tied again (43:30)
At the start of the movie, when Jackie and the commandos are attacking the convoy, they do a visual survey with special binoculars first. This shows people inside the vehicles via individual's body heat. If this is the case, there should be certain parts of vehicles that should appear as red, like a truck's engine block which would have five times the human body heat easily. Also friction would cause the tire treads to have some heat as well.
During the chase scene, the rally driver sets the hand brake, then uses the rear wheels to pelt the assailants with rocks. The hand brake locks the rear wheels, however, which would cause them not to spin. Furthermore, the vehicle (a Mitsubishi Lancer Evolution IV) is all-wheel-drive, which would cause the front wheels to spin as well (as is visible in a previous shot).
The camera gun would be more dangerous to the user than any potential target. Since it has no barrel and the lead is heavier than the brass, it would send fragments of casing back at the shooter.
Asian stuntman in place of Morgan when he is kicked in the final scene.
Obvious Asian stuntman used for the European hitman on the rooftop, especially after he is covered by the cement powder.
Safety wire visible when "who am I?" slide down the building
When Jackie is falling from the helicopter, the safety wire is visible.
Around 1h21m, when Gen. Sherman (Ed Nelson) swings his cane at Who Am I (Jackie Chan), he misses and spins around a few times. If you pause at just the right moment, the man spinning isn't Ed Nelson but a stunt double.
When 'Who am I' is chased by Dutch police cars in Rotterdam, the sirens by the police cars don't sound like they actually do in the Netherlands.
When Jacki runs up the hill on top of the rocks and screams, "Who am I?" you can see a member of the crew underneath the bridge area. When the chopper shot starts to move around you can see him look up at the camera and move back under the bridge trying to hide.
Most of the car chase in Africa is very clearly shot in Rotterdam. In one shot the landmark Erasmus bridge (the bridge on which the final scene is shot) is clearly visible. The part where they drive down some stairs is set in the "Beurs Traverse" also know as the "Koopgoot", also a very well-known location in Rotterdam. Many other characteristic bits of (urban) Dutch scenery can also be seen.
Who Am I (Jackie Chan) told Christine Stark (Michelle Ferre), "He [his father] also told me, 'respect nature.'" He then throws the CD and its case (both made of plastic) somewhere into the water.