The fictional Nakatomi Plaza is the headquarters of 20th Century Studios, so the studio could use one of its own buildings and didn't have to hold back on stunts and action sequences. While Jeb Stuart was writing the screenplay, he did a tour of the building, and immediately incorporated some of the locations and objects he found there into his script as set pieces (such as the cart that McClane and Karl end up riding during their fight). The company charged itself rent for the use of the then-unfinished building. Some of the middle floors were occupied by legal and administrative departments, so only empty floors were used for filming. Still, the filming of scenes that involved gunfire had to be postponed until after hours because some of the employees from the active floors started to complain about the noise.

The costume department had 17 undershirts in various stages of degradation on hand for Bruce Willis.

In an article for the 30th anniversary of the film, Bonnie Bedelia stated that the first thing she thinks of when someone mentions the movie is Alan Rickman. The two became friends and had lunch together every day while shooting the movie. She expressed how lovely and gentle Rickman was in real life.

The scene where Bruce Willis and Alan Rickman meet up was unrehearsed to create a greater feeling of spontaneity between the two actors.

Bruce Willis received a then-unheard of $5 million fee, which was approved by Fox President Rupert Murdoch.

The scene in which Gruber and McClane meet was inserted in to the script after Alan Rickman (Hans Gruber) was found to be proficient at mimicking American accents. The filmmakers had been looking for a way to have the two characters meet prior to the climax and capitalized on Rickman's talent.

The original poster for the film did not feature Bruce Willis likeness, just the building. The producers originally thought it might deter non-Willis fans from seeing the movie. Posters were later altered after the early box office success.

Alan Rickman's feature film debut.

The addresses and phone numbers depicted on the LAPD dispatch's computer for the Nakatomi plaza management are the actual numbers for management of Fox Plaza, where the film was shot.

The German that the terrorists speak is sometimes grammatically incorrect and meaningless. In the German version of the film, the terrorists are not from Germany but from "Europe". This has been fixed for the Special Edition VHS and later home video releases. The only instances of incorrect use of German are Alan Rickman's (Hans Gruber) lines.

One cop says that John McClane (Bruce Willis) "could be a fucking bartender for all we know". Prior to becoming a well-known actor, Willis was a bartender.

In the German version, Hans Gruber's name is changed to Jack Gruber.

In the German version the names and backgrounds of the German-born terrorists were changed into English forms (mostly into their British equivalents): Hans became Jack, Karl became Charlie, Heinrich turned into Henry etc... the new background depicted them as radical Irish activists having gone freelance and for profit rather than ideals. (This led to some odd plot holes in this movie and continuity problems with Die Hard: With a Vengeance (1995); there, the villain is considered to be the brother of Hans Gruber, yet he's German.) This was because German terrorism, especially by the Rote Armee Fraktion (the Red Army Faction), was still considered a sensitive issue by the German government in the 1980s.

The line "Yippee-ki-yay, motherfucker!" is used in all Four Die Hard movies (this one, Die Hard 2 (1990), Die Hard: With a Vengeance (1995)), and Live Free or Die Hard (2007), although a gunfire masks the 'fucker' part in the latest installment). It also translates in Urdu to "here eat this".

In this film, Hans Gruber mocks McClane, telling him that this time "John Wayne does not get to walk off into the sunset with Grace Kelly." Willis responds, "That was Gary Cooper, asshole," in an obvious reference to the western High Noon (1952).

The terrorists arrive in a truck that is green with a white top with "Pacific Courier" on the side. In Die Hard: With a Vengeance (1995), the truck that gets caught in the blast outside the Bonwit Teller store is a green truck with a white top, with "Atlantic Courier" on the side. Also, in Speed (1994/I), the airplane that gets blown up at the end is green with "Pacific Courier" on the side. This is an in-joke from production designer Jackson De Govia, who was part of the crew for all three movies. Ironically, "Pacific Courier" translates to mean "Bringer of Peace".

This was based on a book by Roderick Thorp entitled "Nothing Lasts Forever" - a sequel to another book entitled "The Detective", which in 1968 was made into a film starring Frank Sinatra. Coincidentally, Bruce Willis made his movie debut in The First Deadly Sin (1980) walking out of a bar as Sinatra walks into it.

Bruce Willis received a then unheard of $5 million, a fee that was OK'd by Rupert Murdoch. Bruce and Demi Moore tied the knot at the Golden Nugget hotel in Las Vegas during this shoot, Moore having recently broken her engagement to actor Emilio Estevez. Little Richard presided over the ceremony and former brat packer Ally Sheedy was a bridesmaid.

Anthony Peck plays 'Young Cop' in this film ("Something about a double-cross"). He later plays the cop 'Ricky Walsh' in the second sequel, Die Hard: With a Vengeance (1995).

Continuity

There is no ambulance in the truck when the terrorists first arrive, but Theo drives an ambulance out of the truck near the end of the movie (error acknowledged by filmmakers).

The FBI sends two helicopters to Nakatomi, but just before the John-on-the-roof sequences, the second helicopter disappears and is never seen again.

John McClane starts off with a clean white tank top shirt that becomes dirty and bloody. Then suddenly it is uniformly brown.

Takagi was born in Kyoto in 1937, yet a computer readout displays his military service assigned to the aircraft carrier Akagi in July 1940. It would be impossible for him to serve the Imperial Japanese Navy at the age of three.

The orchestra disappears. They are playing when McClane is driving to to the Nakatomi Building, they are playing after he arrives and they are again playing when the terrorists burst into the party. However when the hostages are rounded up and later when they are herded up to the roof the orchestra members are nowhere to be seen.



Factual errors

Several times during transmissions with the two-way radios, characters interrupt each other, which would be impossible given the type of radios they were using.

When McClain calls the Emergency Distapch he uses a radio yet the Dispatch operator sees a telephone number on the computer screen.

When McClane drops the monitor with the C4 down the elevator shaft, he has time to jump away from the door as the explosion rises. The gases from C4 actually expand faster than the speed of sound, so his face would have been melted off.

When John sets off the fire alarm to alert the authorities Hans tells one of his men to call the fire department and report it as a false alarm. The fire trucks and emergency vehicles are called off and turn around without ever reaching the building. This is not the usual procedure when a fire alarm is sent via an alarm system, fire departments are required to verify for themselves that there is no fire to prevent the possibility of arson by a disgruntled employee. Even if they are called with a code or speak personally to a building owner, the fire department must verify independently that there is no fire.

The FBi cannot simply take over the hostage situation from the LAPD, nor would any of the LAPD brass allow it, especially not to a mere two FBI agents (Johnson and Johnson). At best, they would try to work together, and there is no way the LAPD would allow the Johnsons the freedom to fly a helicopter over the building and take shots at anyone on the roof.



Incorrectly regarded as goofs

Early in the film, shortly after the terrorists have launched their assault, McClane glances out a window and sees a woman in the building across the street. However, previous and subsequent long shots of the building he's in show that there are no other buildings close by.



Revealing mistakes

At the start of the scene when Hans is threatening Takagi, he is seen removing a noise suppressor (colloquially, a "silencer") from the end of the barrel. However, as the pistol he is holding (a Heckler & Koch P7M13) does not have a barrel long enough to thread a suppressor on on the outside, the crew threaded the inside of the barrel for the production. As Hans removes the suppressor, you can see that the screw used to mount the suppressor would completely block the barrel, rending the pistol useless.

When jumping off the roof at Nakatomi Plaza just before it explodes, you can clearly see John McClane's "rubber shoes" that were used to protect his feet. While the people are being held hostage, he is supposed to be barefoot. His support wire is also visible in addition to the fire hose.

When Hans is holding onto Holly's watch out of the window and then falls, he is shot in slow motion but the paper that is falling in the background is moving at normal speed.

Obvious stunt double for McClane (missing a tattoo on the shoulder) during the fight with Karl.

When John is reunited with Holly, paper is falling around them. This paper is supposed to be the bonds that the gang were trying to steal, however, it is clear the paper is blank.



Miscellaneous

The terrorists launch an explosive projectile twice at the police tank and the same window bursts twice.

When Hans says Bill Clay, his false name to John McClane while they are on the 33rd floor, the camera zooms in on the name directory and we can see the name Aster and under FL the number 39 but the Nakatomi building has only 35 floors.



Audio/visual unsynchronized

When Takagi speaks to the employees at the party they erupt in loud applause. Looking at the employees, none are clapping their hands.

When the swat team is trying to enter the building and they fail to pick the lock, a swat team member clearly lights a cutting torch to burn the lock. A few scenes later you can clearly hear a grinding sound indicating a drill or grinder is being used to try to break the lock.

When John is first chased by a terrorist, up on the floor still under construction, he turns on and off a radial arm saw. The very distinct sound of the blade running against either a kerf in the fence or a kerf in the table can be heard. However, when the terrorist finds the saw, it can be clearly seen that the blade is running free.

When the terrorist car first pulls up to the Nakatomi Plaza, the noise from the brakes is not consistent with the movement of the vehicle.

At the end of the movie we see the building exploding from a distance. The sound of the explosion is at the same time the explosion happens but since light travels faster than sound, it should have been at least a few seconds between the explosion and the sound.



Crew or Equipment visible

After the 911 call gets cancelled, the guard goes to floor 32 where John is. When the guard turns on the lights, the camera crew is reflected in the window.

As John is fighting Karl toward the end of the movie, Karl's harness is clearly visible as he is dragged across the room by the chains which are supposedly round his neck.

When Hans crashes through the window after being shot, and drags Holly with him, the line attaching Holly to the ceiling is visible in the exterior shots looking in.

In the shots that we see of John McClane when he asks the hostages where his wife has been taken to by the terrorists, you can see the pyrotechnic charges taped to the roof that are about to be used. When the helicopter swings overhead and a soldier uses his machine gun, you can see the charges detonating and the fact that they are charges being used to simulate M-60 bullets hitting the roof.

After John hangs Karl in the roof equipment space, in the next shot where he reaches for his gun on the floor and checks to be sure it's loaded, either Alexander Godunov or his stunt double is visible standing atop the stairs behind John, in costume as Karl, in black shirt and pants, watching the scene being filmed.



Plot holes

The "terrorists" plan to get the FBI to cut the power to Nakatomi Plaza so the lock to the vault will open and they can steal the bearer bonds it contains. Any electric device of this criticality would be connected to a UPS - Uninterruptible Power Supply - so even if the utility power were cut it would continue to function.

After McClane kills Tony on the stairs, it was unwise of McClane to confirm a rogue element by sending Tony's body down in the elevator and alerting the rest of the terrorists, he should have just hidden Tony's body and used his kit. The terrorists maybe would have come to investigate Tony's whereabouts but not in numbers, expecting someone with a machine gun, ho, ho, ho.

When the terrorists take over the building they stop the escalators, a pointless step since you can still use a stopped escalator.

When McClane throws the corpse out of the window, Sgt. Powell's car is many metres away from the building. It's hard to believe McClane could have thrown the corpse far enough to land on the car, especially with such perfect aim. From 33 stories (110 m) all he'd need is be a shove to angle the body 5? to hit the car 10 m away. Basic geometry.

Since Richard Thornburg interviewed a minor without parental consent Channel 9 wouldn't have been able to air the interview with Lucy McClane therefore Hans Gruber wouldn't have known Holly Gennaro McClane, John McClanne and Lucy were related to each other.



Boom mic visible

Just after we are first introduced to Johnson and Johnson, Hans is seen walking on the top floor in, looking up and shining his flashlight. In the Forward Tracking Shot, just before he climbs the wall, the shadow of the boom mic is visible just above his shadow on the far right of the screen in the widescreen version of the film.



Character error

When the terrorists are first walking in as a group looking very serious and sinister, the one on the far left is on a collision course with the wall! The camera cuts away just before he walks into it.

When the SWAT team is trying to break into the front door of the tower they first try picking the lock to no avail. Then we see a SWAT team member carrying a metal cutting torch attempting to cut through the lock. The SWAT team would have just broken the glass to get in and not waste time using a metal cutting torch to cut the door lock. The glass is obviously breakable as shown in the same scene when the terrorists fire upon the SWAT team.

When Theo updates Hans on the police activity, he reports that "the four assholes [are] coming in the rear in standard two-by-two cover formation." The SWAT team members are not in '2x2 cover', they're all running together single file (more or less).

Holly's maiden name is correctly spelled 'Gennaro' in the computer system, but, when John taps it on the screen, it changes to 'Gennero'. It is also misspelled as 'Gennero' on her office door.

Takagi mentions that any computer information Gruber gets would be changed "when they wake up in Tokyo in the morning". Japan is 17 hours ahead of Pacific Standard Time, so early evening in California corresponds to roughly midday in Tokyo. The workers wouldn't need to "wake up" at all because they'd already be at the office.