Revealing mistakes: Obvious fake knife that Jack holds between his teeth.
Continuity: In Gracie Law's apartment after Miao Yin is kidnapped, Gracie is holding a pitcher. As they get ready to leave, Jack Burton hands the pitcher to her.
Continuity: During the fight between the two Chinese gangs, Jack and Wang are sitting in the truck's cabin. But in external shots of the truck, there's nobody inside.
Audio/visual unsynchronized: Jack's truck has an overhead pull line for his air horn (seen on-screen when the Puma truck cuts them off). Early in the film, when Jack is pulling into the Chinese market, you can clearly see that he's *not* pulling that line when the truck's horn sounds.
Continuity: When Jack Burton is explaining what happened in the alley, he mentions that Lo Pan had "light coming out of his mouth". However, Jack could not have seen this, as he was already temporarily blinded by the light from Lo Pan's eyes, and had his hands over his eyes by the time the light came out of Lo Pan's mouth.
Revealing mistakes: Lo Pan's supernaturally tall form is revealed to be nothing more than a pair of high platform shoes when he falls.
Audio/visual unsynchronized: When Jack shoots the lock off of the first line of cages his gun fires twice before the first sound of a gunshot is heard, then at least three more times, again with only one gunshot heard.
Continuity: When Lo Pan encounters Gracie, who is just seeing the floating Mao Yin, Lo Pan's pinky-nail is as long as the others for just one scene. In all of the other scenes his pinky nail is extended.
Crew or equipment visible: When Jack Burton is kicked through the air by one of the three storms, padding can be seen through the shirt of the stuntman before he hits the chair.
Continuity: In the first fight scene in the alleyway that Jack and Wang witness, the same stuntman can be seen charging, fighting, and indeed being KO'd alternately dressed as a Chang Sing, or Wing Kong.
Continuity: When Jack, Wang et al exit the Wing Kong Import/Export Exchange Company, Uncle Choo is waiting outside in a yellow bus. Wing Kong security then open fire on the bus as it drives away. However, as the bus turns a corner seconds later you can see that there aren't any bullet holes or broken windows on the side of the bus they were shooting.
Continuity: When Jack and Wang are rescuing the girls and a fight breaks out in the white plaster storage area, they use the same shot twice when one of the bad guys is kicked and lands on a table against a wall.
Continuity: When Thunder is chasing after Jack and Wang the color of his undershirt changes.
Plot holes: During the wedding ceremony, Lo Pan can clearly be seen grabbing Miao Yin's wrist to prick her with the ceremonial needle. However, the entire purpose of the ceremony is to lift his curse and return Lo Pan from his current ghostly state to flesh-and-blood. He should not be able to grab her wrist until after the ceremony is completed.
Crew or equipment visible: When Jack Burton rolls backwards in the wheel chair that stops and is teetering on the edge of falling into a well, you can clearly see the wires holding the chair in place to keep it from falling.
Continuity: In preparation for the "blade test" of Gracie and Miao Yin, Thunder steps toward them while performing a martial-arts display with two curved blades. As he reaches the women, we see him from behind as he sets the blades on the floor. When the POV changes and we see him from the front, the blades are not there.