Continuity mistake: During the scene when Mr. Devlin is in De L'Air, the bug store, the eyes of the young black woman with whom he is speaking change back and forth from blue-gray to brown. (00:15:18)
Continuity mistake: The back of Jennifer Love Hewitt's gown at the final party changes from when they are dancing when they arrive to when they are kicking butt in the lab.
Continuity mistake: When Jimmy was in a fight with the mean biker dude, the guy punches and shatters the driver's side window of Jimmy's taxi. After the fight, when Jimmy is driving a woman, the window is perfectly intact.
Continuity mistake: At the party right before Del Blaine and Jimmy Tong find their way down to the lab, Del is wearing dress sandals. When they get to the bottom of the stairs, she's wearing wedges. Her shoes change several times throughout the rest of the evening, including a third pair of chunky heels.
Continuity mistake: In the fight scene on top of the oil building, just after Jennifer Love Hewitt roundabouts the guy, she grabs Jackie Chan's hands, her hands are on either side of a pole. In the next shot, zoomed, their hands are on one side of the pole.
Revealing mistake: In the scene where Jennifer Love Hewitt and Jackie Chan are on the top of the building, trying to plant the bug on the briefcase, and the men all attack, as Jackie is hanging over the edge Jennifer has a man on his knees. If you watch closely, or in slow mo, she is about two feet away from actually hitting the guy.
Continuity mistake: Jennifer's hair when Chan is fighting and holding a glass against her face changes from light brown in the close shots to dark brown-black in the wide ones.
Continuity mistake: In the funky singing scene the flower that Jackie's wearing is pink. Afterwards, at the kitchen, it is red.
Plot hole: When Delila finds out who Jimmy really is, she takes his tuxedo and is apprehended by the bad guys. She then turns on her homing device on her necklace. The office says it will take 20 minutes to get to her. From that statement to when the CSA finally arrives, Jimmy has time to go to Devlin's, write him a letter, discover water striders, find his suit, and get back to Delila and fight the bad guys. THEN CSA shows up. The timing is really off.
Continuity mistake: When Devlin gets attacked, the big flow of blood on his head and face is totally different in the brief side shot we get and back to bleedy in the next front angles.
Continuity mistake: In the scene when Jackie Chan gets out from underneath the cab his back is dirty. in the next shot when he goes in to the back seat of the cab to lay down his back is clean. (00:07:45)
Continuity mistake: When Chan hangs the mink coat on the coat hanger its position differs between shots.
Continuity mistake: When Jimmy is driving the woman to work, he does a hand brake turn into an alley way and hits the wall with an audible crash, yet when he drives out of the alley there is no damage to the side of the car.
Plot hole: Near the beginning when the bad guy is testing out his "new formula" on his employee, his explanation of how the bacteria worked could not have caused the effects seen on the man. Genetic material couldn't be incorporated into the host that quickly and besides, pumping electrolytes into the bloodstream may cause death but that would not remove any of the water - it would still be present in the cells and so the poor chap wouldn't be turned to dust in that way.
Continuity mistake: When the man drinks the poisoned water his face gradually dehydrates, becoming wrinkled and grey. However, when he kneels on the floor his skin colour is perfect and the wrinkles are gone.
Continuity mistake: The water that Chan spills on the picture of the bug appears and disappears all the time.
Continuity mistake: In the scene on top of the building when they are planting the bug, the guy grabs Blaine with his left arm around her neck. However, when she bits him, she bites his right shoulder.
Continuity mistake: When Chan and Jennifer are watching the map with the dams, they are standing a couple meters apart, but very close together a frame afterwards.
Revealing mistake: When Chan is trying the tuxedo for the first time, he activates de ingravid mode and then falls down from the ceiling. The falling mat is noticeable under the rug, because it's flat in further shots.
Continuity mistake: In the last scene, a man with a grey coat with blue and red stripes on the sleeve walks from left to right behind Jennifer. Shot on Chan, then cuts to Jennifer just 2 seconds later and the man walks by again, also from left to right.
Chosen answer: Since Del knew that the tuxedo actually belonged to Clark, she most likely thought that the watch and shoes did too.