Other mistake: When Bruce is looking on the touch-screen computer to find out where his wife is, he touches the name GENNARO, but when it changes colour it also corrects the spelling of his wife's name to GENNERO. (00:09:25)
Other mistake: In the shot where we see all the terrorists (except Karl and Theo, who are upstairs) walking into the building from downstairs, they are about to walk through a doorway when the camera cuts out. Watch the terrorist on the left (he's the one who guards the door) - the way he's walking he's going to smack straight into the wall! The shot cuts a fraction of a second before he does, but that's not a remotely normal walk/position - it's clearly just because it makes for a cool looking shot. (00:18:15)
Other mistake: Powell says he has a desk job, but he is driving a cruiser. Cruisers are for cops on patrol. A cruiser would not be issued for a cop at a desk, especially not one who's on his way home, as Al says he is.
Other mistake: After Powell frantically radios in his distress call, other police cars converge on the street in front of Nakatomi Plaza, blocking off both sides of the street. But when McClane grapples down the building using the firehose, you can see traffic on the street below and none of them are police.
Other mistake: Near the start of the film, when John goes to meet his wife at the office block, there is a party going on and a small orchestra playing. When Gruber and his gang enter, the orchestra are still there. Gruber locks down the building, and takes the guests hostage. Where does the orchestra go after that? They are never seen again, even when the hostages are taken to the roof.
Other mistake: In the computer room shoot-out the bad guys shoot out all the glass room dividers in a hail of bullets, but the glass windows on the exterior of the building (behind the dividers and in the path of the bullets) stay intact; they don't even get scratched.
Other mistake: When John is on the roof being shot at, he shoots the lock off a door before charging through it. We see a close up of the door as it's shot, and there's a blood smear already on it. He then goes through it shoulder first, which is what would leave a smear like that - must be from an earlier take.
Other mistake: All of the lights on one of the Christmas trees stay on throughout the movie, even though the power was cut, and only emergency lighting supposedly was left on.
Other mistake: When the terrorists shoot the armoured vehicle from high up in the building, the angle at which the rocket launcher is fired seen from inside the building is simply wrong for a target that is virtually directly below them. The angle shown would have hit much further away. This is true for both shots but more obvious for the second one.
Other mistake: McClane's undershirt is white for the beginning of the movie, but when he emerges from the air conditioning ducts, it is now a dark colored shirt (it looks very dark green) with a lot of stains on it. If this is supposed to represent the same shirt, just very dirty, it could not have come from the A/C duct work, for it was all brand new and the interior shots showed it all to be spotlessly clean. The change in appearance is far too abrupt to be possible.
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.