Deliberate mistake: When McLane pulls out the phone he shot up after he and Zeus get into the Yugo there are a lot of coloured long curly cables hanging from the damaged phone. Mobile phones of this era would not have had any of these cables inside them, it is a deliberately made prop.
Continuity mistake: During the car chase between the Ram and the Mercedes, the Mercedes is going around a red Plymouth Acclaim, but in the very next shot it is a Chevy Cavalier. The Ram truck then starts scraping between the wall and the other side of the Cavalier, but when it cuts to a close-up it is now hitting the side of a grey Buick that was in front of the Cavalier.
Revealing mistake: When the water is pushing the truck in the aqueduct, one scene shows McClane on top of it. The truck and McClane are a different color indicating they were superimposed into the shot.
Continuity mistake: When they're on the bridge, trying to find a way onto the barge and they first get out of the truck, the skies are very overcast, as shown by the rain on the bridge. When they cut away and cut back to McClane, the sun is now out and very few clouds in the sky. It's fairly obvious that it was shot on different days and the bridge watered down.
Visible crew/equipment: When Zeus and John get the cab after being attacked by the group of dudes in Harlem, as they are riding to the police station you can see the camera truck out the back window of the cab.
Suggested correction: How do you know that's a camera truck? Could be just any regular truck passing by.
There is a camera held out of the passenger side window of the van.
Continuity mistake: In the subway scene, when carrying it before it starts to mix, the door is hanging off on the left side. When it starts to mix, the door is hanging off on the right side. There could be some time that he could rotate it, but with him using his left hand to tell people to move to the front of the car and grabbing the poles, he wouldn't be able to rotate it.
Revealing mistake: When Simon is in the helicopter and shoots at McClane, check the metal strips next to his feet and the protruding metal parts where the squibs have been placed to allow for the pyrotechnics.
Visible crew/equipment: When Simon and Katya are in the helicopter, both are replaced by obvious stunts. Simon has dyed blond hair as opposed to his brunette stunt, while she has short and straight hair, but her stunt's is long and curly.
Continuity mistake: When McClane (Willis) approaches the dump truck in the aqua duct, the driver pulls an Uzi submachine gun onto his lap. The camera then cuts to McClane being seen in the door mirror of the truck, then cuts again to the cab being shot full of holes by McClane. The gun on the driver's lap changes to an MP5K (in this case, a Daisy MP5K Airsoft Replica).
Continuity mistake: The sun is coming up behind McClane at the end. Particularly noticeable in the shot where McClane is shooting at Simon. The previous and following shots show a black sky.
Continuity mistake: The damage to the sedan during the shootout on the road changes. The windshield goes from being normal to full of cracks.
Revealing mistake: Towards the end of the film when Simon and his men are found by McClane (Willis) and Zeus (Jackson), Simon's men can be seen taking MP5K submachine guns. The guns are actually Daisy MP5K Airsoft replicas. At one point, a man "pumps" the forward grip of the gun to cock it. Indicating it as an airsoft gun and not a real submachine gun.
Continuity mistake: When the cab drives between the two trucks it comes out without a scratch. When it crosses the park it is damaged all over.
Continuity mistake: After exiting the aqueduct, McClane falls in a puddle, hair slick, soaking wet and covered in mud. Zeus calls him and McClane turns around. In a brief shot from behind him his hair swaps to clean and fluffy.
Visible crew/equipment: At the very beginning of the film a bus passes the camera. A reflection of a crew member is visible. Its fast but clear enough to see that he has his arms crossed.
Continuity mistake: In the taxi, when Zeus is telling John his name and asks if he has a problem with that, John's hand is not against his head. In the next shot it is.
Character mistake: Why didn't Joe, Connie, and the students just run back down to the front entrance of the school? They had plenty of time instead of making the effort of going to the roof.
Suggested correction: No, they couldn't. They barely made it to the roof on time and that was closer than the front entrance.
Continuity mistake: The cab drives in between two trucks and drives further up. When McClane says "I didn't say Park Drive" watch the rear window and the truck he passed by 50 meters away is now really close behind.
Continuity mistake: Before the cab drives through Central Park McClane slams on the brakes. Skid marks from previous takes can be seen on the pavement.
Revealing mistake: After McClane chases the ambulance in the cab, he is driving the wrong way down a one way street. Notice the tyre marks on the pavement from previous takes. The cab follows them to a T.
