At the end of the snuff movie shoot in the garage the actor being hoisted up on the meat hook changes from the bearded, brown haired actor to a dark haired clean shaven Chinese stuntman.
Some of the movies Jake watches in New York (featuring Khan wearing a bib) aren't shot until later in the movie (the garage fight scene).
In the final fight Jake hits Khans head with the sword. Khans mask is cleanly cut in half like the sword had cut right through his head, yet Khan has only a small scratch.
When Prang's dead body is thrown into the water by Khan near the end of the movie, you can see pieces of cotton wool stuck up his nose to prevent the water from entering.
Obvious Chinese stuntman at the end of the movie when Loren Avedon is flying through the air while holding the pole.
Molly's mouth doesn't move when she screams "Jake" a couple of times in the net.
In the final fight a black haired stuntman doubles for Jake several times, most prominently when Khan is on the ground and Jake tries to jump on him, and when Jake is on the pole.
Billy Blank's character Khan was written in the script as being part Thai. Nevertheless he doesn't speak one word of Thai throughout the film.