The Replacement KillersGoofs
After John and Meg escape from Wei's gang, they return to John's hideout, where he treats her dislocated patella - which looks amazingly like the real thing, makeup or no. John pops the kneecap back into place with no difficulty. However, anyone who has ever suffered that particular injury knows that it would be impossible to immediately stand, walk, run and jump as Meg does when the evil-doers subsequently chase them from the apartment. The tissue damage involved takes weeks, if not months, to heal enough to allow that kind of activity.
During the shootout at the arcade, Ryker uses an MP5K in a briefcase. If the briefcase were actually used in this manner, the shooter would most likely end up with a calf-full of lead. The proper technique of employing an MP5K in a briefcase (as taught by the HK International Training Div.) is to hold it with both hands and brace it against the chest/stomach (muzzle toward the target, of course).
At the airport when the different incoming and outgoing flights are shown, flight RK 27 from Melbourne and Flight NK 611 to Sydney are incorrect. Flight RK was owned by Royal Khmer airlines (started operations in 2000, 2 years after this film was made and never flew in Australia.) Flight NK is owned by Spirit Airlines and likewise has never flown in Australian airspace.
In the final scenes after the shoot out at the end, when Zedkov runs into John and Meg in the stairwell, Chinese characters are clearly visible all over the walls. However, in a few cuts during the confrontation, a two syllable Korean word is clearly painted on the walls. The word is "bah-boh" which loosely translates to "Dummy" in Korean.