The cuts on Ah Keung's face disappear in one day.
On top of the parking garage, the owner of the truck that gets pushed over the side of the building is first pictured wearing a cap with a rebel flag design and in subsequent shots of the same scene his cap has an American flag design.
The hovercraft's windows reappear after being shot out.
When Keung asks Danny if he's okay, Danny's chin is bleeding. After Keung has beaten the "suit" henchman, Danny is smiling with no blood on his chin.
When the hovercraft ploughs through the intersection, the cars in the far left and far right lanes switch positions between shots.
At about 48 minutes in there is a handwritten sign in the shop that is being attacked that reads "potatoe CHIPS". There should be no 'e' at the end of potato.
When the gang chases Jackie on motorcycles, Tony begins to chase him on a motorcycle with the number 36. However, after a while, the motorcycle 36 is no longer sitting Tony, but a bandit in a helmet. He is trying to hit Jackie, and he dives head first into the hatch of a sports car. But after a few seconds, Tony turns up on this bike again.
Danny's Sega Game Gear, given to him by Keung, has no game inside it. In spite of this, Danny seems to enjoy playing with it.
The soda pop display that gets knocked down in the supermarket is obviously made from empty cans.
On the beach, when Keung throws the child to her mother to save her from the hovercraft, you can clearly see that it is a dummy.
The same background vehicles are used repeatedly throughout the film during major action sequences on the streets. Most obvious are a red Mercury Bobcat, beige Ford Thunderbird and red Ford Granada, which appear, along with other vehicles, multiple times during the hovercraft chase, and earlier in the parking garage scene. Vehicles that are hit and damaged show up later parked or representing other vehicles, including the Dodge Diplomat police cruiser struck by the station wagon at the intersection; this reappears shortly after as the police unit hit by the hovercraft along with Harrison's unmarked car (identical damage from the earlier scene is visible). Furthermore, two of the unmarked police cars (the red Plymouth Caravelle and gray Chevrolet Caprice) are inconspicuously used as parked vehicles several times throughout the hovercraft chase, most obviously at the beach where Keung runs across them to jump aboard the craft.
When driving from Kennedy Airport to the Bronx the way Uncle Bill (Bill Tung) did when picking up Keung (Jackie Chan), one doesn't have to drive through downtown Manhattan to get there.
When Keung kicks the glass bottles off the pool table, there's no sound of the bottles hitting the floor.
In the club in which Nancy danced (when Kyong went to talk to her), dance music is played. Then why was there also a rock band playing with guitars, bass and drums, and why can't they be heard? It is also obvious that this group does not play in harmony with the dance song.
The blue motorcycle with the Christmas lights is a Yamaha RZ350, but does not sound like one.
Apparatus for rotating bus visible under bus. Front end of bus clearly elevated to facilitate the rotation sequence.
Camera in the back of beige Chrysler as it swerves around the oncoming hovercraft.
After the hovercraft hits the bus, you can see a camera next to the bus driver.
Set in the Bronx, obviously filmed in Vancouver.
Even though the movie is set in Bronx, NY, during the scene where the truck full of balls is pushed off the parking garage you can see the Vancouver's mountainous coastline.
The hovercraft is an ex Canadian Coast Guard hovercraft with Canadian registration beginning with CH, even though it's set in America.
Although set in America, when the hovercraft reaches the beach and comes to a stop, the helicopter hovering in front of the bow has a Canadian registration.
When the tow truck is hooked to the grocery store the side of the truck say's '"Langley BC"