Goofs

McClane uses a mixture of the binary liquids to blow the handcuffs off Zeus on the container ship. The amount he uses would have been enough to blow at least one of Zeus' hands off (in comparison to the amounts used as a demonstration earlier on in the film).

While John and Zeus race toward the subway in a commandeered taxi, John is forced to drive between two vehicles that are too close together to fit the taxi. Upon slamming through, both side mirrors are ripped off and scuff lines are made on the side of the car. In every shot afterward, the mirrors are still intact. However, the scuff lines remain.

Simon tells McClane and Zeus that the phone at Wall Street station is next to a news kiosk. But when Zeus gets to the phone, it's under the stairway and not next to anything.

When John is looking for the bomb on the subway he under the seat of a blonde woman wearing a light tan dress, later when John throws the bomb from the train, THE TRAIN HASNT STOPPED YET and the same blonde woman wearing the same light tan dress is already standing on the subway platform running away from the explosion.

The make of the truck changes in the aqueduct scene. John McClane is driving an Autocar truck but one shot showing the water catching up to the truck shows a Mack truck.

New York City subways do not provide direct unlocked access to moving subway trains.

When McClane and Zeus are in the Mercedes, McClane asks Zeus to disconnect the ABS brakes so he can spin the car, and tells him to pull out fuses from the fusebox. The fusebox on a late '80s S-class Mercedes is not where Zeus finds it (it's under the hood) and if you pull fuses at random, the car could be rendered undriveable (fuel pump fuse, for example).

On standard truck winches, like the WARN winch used on the Dodge truck, the manufacturer recommends that at least five complete wraps of wire remain on the drum as the minimum to make a safe winch pull. So if the winch cable "ran out" as it did in the scene, as the truck started to get pulled, the only thing holding the winch cable onto the winch drum is a small bolt. If the weight of the vehicle is applied to that small bolt (versus the other end at a static object), the winch cable would have snapped off.

It would be impossible for the water flowing through the tunnel to propel the dump truck through it.

The train that John McClane intercepts with the bomb is a red #3 train. #3 trains are all silver.

Charlie explains that the bombs use a binary liquid, and detonation occurs after the two liquids mix together. However, on the subway, the two liquids start to mix before the train hits the switch on the tracks. This means that the bomb would have detonated whether or not the train hits the switch, rendering the trigger unnecessary. This is not necessarily a goof because during Charlie's demonstration the mixed liquid does not explode until triggered with something (in the demo it was the physical impact). The mixing merely primes the liquid, making it ready to be detonated thus the trigger was necessary.

When McClane and Zeus are driving through the park, you can briefly see the tire tracks of the taxi from a previous take.

At the Elephant Water Fountain scene, a white truck driving in the background has a passenger in a blue shirt leaning out of the window and keenly observing the goings-on.

When Katya begins to drill on the "wall" between the subway and the bank vault, you can clearly see the wall reverberate because it is, most likely, made out of plywood

When the mercenaries are gathered in the warehouse near the end with the trucks filled with gold bars, one of them opens a truck and bars spill out onto the ground. One of the bars is clearly an unpainted lead bar.

When the Mercedes rolls, it is possible to see on the upper right hand side of the screen the wire which pulls the car over.

Binary explosives look cool and sound high tech in movies but in reality prior to the two liquids mixing there is zero danger of explosion. It would be far easier to disarm than a regular bomb.

During the elevator shoot-out, the final bad guy McLane shoots remains pinned to the wall by his face even though McLane is no longer pressing him against the wall and he is free to turn around as he shoots his gun.

Stunt man noticeable where McClane drives car on sidewalk on the way to stop train blowing up.

In the first part of the movie when the bus rolls by before the building explodes, you can see the camera is briefly visible along with a guy in a black shirt and blue jeans.

Stunt man noticeable when McClane is catapulted up from the aqueduct through the manhole.

In the cab, when John and Zeus are introducing themselves, out the back window you can see an SUV going in and out of the picture. There's a crew member with a camera pointed out of the passenger window.

There is a dark-haired woman from the filming crew crouching in the smaller boat in which the terrorists are escaping before the bigger boat explosion.

The ship travels from Hudson River to the middle of the Long Island Sound in an impossibly short time.

At one point the dump trucks are supposed to be traveling on FDR Drive. The FDR is for cars only and does not allow trucks. The dump trucks would not only have been pulled over, but they would have been too tall to clear many underpasses and tunnel entrances as well.

The dump trucks are supposedly heading north on the FDR drive, however, Simon's truck approaches a sign that says "Cadman Plaza West". This is a sign on the Brooklyn Queens Expressway in Brooklyn, across the river from the FDR drive.

Simon and Katya are making their escape from the cargo ship supposedly in Long Island Sound. The boat they lower off the side has a hull identification number starting with CF. These letters stand for "California Fleet" and are only used on boats in California.

Zeus drops off his "passenger" at Trinity Place and Cedar Street. Wall St Station is 0.3 miles away. There are 3 stations closer to this intersection.

A drive from New York City to the Quebec border takes about 5 and a half hours - probably slightly more if driving a truck. Even if Simon's henchmen did have a head start, they would still be somewhere in New York state by the time McClane figures out their destination. That would have given American authorities plenty of time to intercept the trucks along the way inside their own borders. Moreover, even if the trucks would have had the time to make it to the Canadian border, they would have been caught by customs with a very suspicious cargo of bulk gold bars.

Ricky Walsh is present during the meeting in the van with the FBI, sitting in the front passenger seat and would have a clear unobstructed view of the pictures of Peter Gruber and Mathias Targo in the FBI folder. So he could have easily identified Peter Gruber when he introduced himself as Bob Thompson from the City Engineer's Office. He also takes a good glance at Mathias Targo when he jumps on one of the trucks so he could have easily identified him as well.

SImon alleges that "one ounce more or less" than four gallons will result in detonation. This is greater than 0.2% precision, which rivals that of well-manufactured volumetric glassware and is unlikely to be achievable with cheap plastic jugs. Furthermore, there does not appear to be a fill line on either jug, making a precise measurement impossible.

Simon tells McClane that there are $13,000,000,000 of gold in the dump truck. This would mean, at gold prices for 1995 ($400 USD an ounce) that the dump truck is hauling 1015.5 tons. According to dieselpowermag.com 10 Largest Dump Trucks page (these are the massive open pit mining dump trucks) they carry anywhere from 400 to 280 tons. The Federal Reserve Bank holds about 5000 tons, equally divided by 14 dump trucks would mean each truck is hauling just over 347 tons (still more than the dump trucks in the movie could haul) and worth only $4,500,000,000.

When John and Zeus are in Tompkins Square Park they see that they are being sent to Yankee Stadium, and thus John says, "Where is the nearest A train?" The three subway lines that go to Yankee Stadium are the B, D, and 4. At Tompkins Square Park the closest subway line to them happens to be the 4 train, regardless of their destination, thus it would not even make sense for them to walk across town to the A train and transfer lines at a later point.

Simon refers to McClane as Lieutenant and Detective. Lieutenant and Detective are different ranks and neither the rank of Lieutenant-Detective or Detective-Lieutenant exists in the NYPD.

The vault guard in the Federal Reserve Bank radios his captain during the break in, however the person who replies is wearing lieutenant insignia on his collar.