Continuity mistake: Takagi leads John inside Holly's office. A shot later Takagi has moved several meters behind and is holding the door knob.
Continuity mistake: Hans leaves his gun and flashlight lying on the ledge out of sight. When he edges back to get it, the gun is upright, easy to grab.
Visible crew/equipment: At the end when all of the papers are falling from the building, there is a wide shot. On the right hand side of the shot looks to be some kind of blower machine making the papers come out.
Revealing mistake: When McClane is on the roof shooting over the hostages the helicopter appears and they start shooting at McClane, the squibs used for the helicopter shooting scene are visible lying on the roof and explode in sequence, starting at the back and moving toward the camera as McClane does.
Continuity mistake: When McClane goes onto the roof at the end he shoots Uli as he opens the door and the blood splatters all over the wall at the side, but when McClane walks past the body there is no blood on the walls or steps or where the body is lying.
Continuity mistake: When the terrorists arrive the truck reverses up to the loading bay and a tail lift is deployed, but at the end when the ambulance is unloaded the tail lift has been replaced by ramps. Tail lifts are bolted to the truck frame and simply cannot be removed.
Visible crew/equipment: McClane runs up the stairs and looks on floor 31. He goes up another floor as the camera follows. The camera operator's shadow is blatantly visible left screen.
Visible crew/equipment: As the terrorists arrive, there is a shot of two vehicles pulling up. The camera is tracking along with the vehicles. At the very end of the shot its shadow and a crewmember's shadow are visible on the concrete.
Visible crew/equipment: When McClane steps out of the Limo at Nakatomi, a large film light is reflected in the door.
Character mistake: When John is informing the police about the terrorists, Franco tells Han "we have to find him and shut him up, he's telling them everything" and Hans says that they will, but then incorrectly refers to him as Fritz. Fritz is the long red haired terrorist.
Continuity mistake: Karl comes in to tell Hans that Marco is down on the street and that the bag is missing containing the detonators. Hans then picks up the radio and switches channels to talk to Theo. Right after that we hear Powell on that same channel trying to reach out to John. How could Al be on the same channel as Theo when Hans was just talking to John minutes before on a different channel?
Continuity mistake: When Argyle is sitting in the back of the limousine he hears on the news that terrorists have taking over the Nakatomi building and that their means of communication is through the use of CB radios that they brought with them. Argyle then moves to the front seat of the limousine and turns on the CB which is immediately tuned to that exact channel.
Continuity mistake: Argyle is seen driving the limo around the garage after hearing that the terrorists have taken over the building. During that scene there are a couple of shots where the back window does not show anyone or anything in the back. But after the limo stops, he looks in the rearview mirror and the bear is sitting with it's head over the back of the seat. This would have been noticeable in the driving shots.
Character mistake: A waiter offers John champagne but instead gives him what looks like red wine.
Continuity mistake: In the outdoor shot where the lobby is being blown up after John drops the explosives down the elevator shaft, the stairs in front of the building disappear for a brief second.
Revealing mistake: When John McClane jumps from the explosion in the elevator shaft, you can see that it is not Bruce Willis but his stunt double.
Continuity mistake: When Theo is at the computer, locking the building down, the pens in the pen holder keep changing positions throughout the various shots.
Continuity mistake: When John and Karl are fighting, after John is shot, the amount of blood on John's arm changes. When John's back is toward the camera there's hardly any blood, then when he's facing the camera his arm is covered in blood.
Visible crew/equipment: When the car and truck drive upto the building, the truck goes down a ramp - another moving shadow can be seen cast over the car, from the camera crew.
Continuity mistake: In the scene where Sgt Powell is entering his patrol car after checking the building, you can see that the spotlight is missing from the car exposing the mounting holes. However, after the body has landed on his car and he retreats rather quickly, the spotlight is back on the car.
Answer: We don't know what John would have done in that circumstance. Obviously Hans was planning to kill everyone with the explosives anyway at the end. Perhaps John would have suspected that. Also, doing that would invite more police incursions.
Greg Dwyer
Hans thought Ellis was a good friend of John's and John still didn't give up when he was going to shoot him. If John wouldn't save his friend, why would he care about others. Plus Hans told Karl earlier he could stall the police but not if they heard gun shots. The police would have absolutely stormed the building if he started killing the hostages.
Zorz
The fact that we don't know how John McClane would have acted doesn't remove the fact that it would most likely have been a good way to coax him out. Also, depending on when Hans Gruber would have decided do implement this strategy, John probably wouldn't have known about the explosives on the roof as he only finds out about them at the 3rd act break. As for the "more police incursions" part, I couldn't disagree more; Hans already killed two hostages - one on speaker with the police -, all the cops in LA seem to be there already, and don't forget that the involvement of the FBI is part of their plan anyway. This is definitely the one major plot hole of this otherwise perfect film.
It would have been, but plenty of movie plots don't pan out the "perfect" way without it being a plot hole. Killing Ellis is a reasonable first step, it doesn't work, and then the events of the plot pick up pace - Gruber goes to check the detonators, as that's a priority. He's hoping/assuming they can get through the rest of their plan by isolating McClane, or at least prevent him causing more chaos. They want the power shut off - they don't want to cause such massive carnage that the building is stormed before then. They need to get helicopters, blow the roof, and escape as planned. Hans doesn't want to derail things any more than they already have been.
Jon Sandys ★
Seems to me like they have all their bases covered; the police isn't even able to get in with a tank as he blows them up so I don't think the police "storming the building" is even a possibility in the reality of the film. Also, after blowing up that tank, that's two hostages and a bunch of cops dead so I would say the situation is pretty derailed. Everything is going as planned for Hans and his team, except for McClane, so he should be in damage control mode and this is an obvious solution. He doesn't even have to change his plans, just tell McClane he's gonna kill one hostage every 10 minutes until he shows up unarmed and tell one of his henchmen guarding the hostages to do it while they go along with the plan and maybe even try to find McClane at the same time. I think this is something Hans should have at least considered, but the screenwriters just didn't think about it/didn't want to address because they couldn't think of a good reason for him not to do it.
There are no cops dead, Hans says "Just wound them" and despite the awesome explosion, the APC isn't actually penetrated or destroyed. But Hans needed this to turn into a standoff, a show of force would prevent a SWAT raid from expediting the deadline, he needed to get all of the hostages up on the roof to make his getaway downstairs, and executing a bunch of them would bring suspicion onto how cooperative he is (His plan to blow up the roof relies heavily on the police sending in choppers) they cooperate with him, which they won't do if they think Hans is a crazed lunatic who's only interested in more and more carnage, if he wounds the cops and only shows he can defend himself, and that he was being reasonable. The cops would play ball, and they would believe he's willing to spare the hostages lives, plus he always planned on taking one hostage as a contingency, if they thought they were gonna be killed they'd become a liability. Patton Oswalt talks of a real plothole though lol.
John McClane would know they'd kill him as soon as he shows up, as soon as he heard "We'll have to tell Karl that his brother is dead" he knew that all bets were off, he lost his chance to end it civil, if they had no personal connection to the first terrorist John kills then maybe putting 5 people into a room and doing an Air Force One on them would work, but not when John knows he'll be body number 6. Al says it best "If he gave himself up they'd both be dead" with Ellis execution, John watched them take control of the hostages, watched them execute the Takagi, and when the first Terrorist thinks he's found John he shoots first after saying "I promise I won't hurt you" and then taking his bag and realizing how well financed and equipped, these guys weren't domestic terrorists, they used serious money, serious contacts, and serious planning to get themselves into this building on this night. He knew the only way to play ball with them was fists and elbows.
Just because a character doesn't do a thing I doesn't make it a plot hole. The plot was that he didn't do it. You may consider a different approach "better" but that's irrelevant. You may as well try to argue that any character choice that doesn't fit with a perceived meta is a plot hole. It isn't, it's just the plot.