Question: It is quite obvious that both Hans and Karl are Germans. So how is this possible that, when Hans ordered Karl to shoot the glass (Schieß dem Fenster) in German, Karl didn't understand it? He complied with this order only after Hans repeated it in English.
Question: Were the terrorists intending to blow up the entire building, as opposed to just the roof, to fake their deaths? If that's the case, then how can they continue with the plan to fake their deaths if McClane already took some of the explosives on the lower floor?
Answer: They were planning to blow up just the roof, with the hostages on it, while they (Hans and crew) were safely below, to make law enforcement, the FBI, etc. think they'd been killed along with everyone else in the roof explosion. The plan was to then escape with the loot in the ambulance that Theo was driving and flee the country before anyone could discover their bodies were not among the scores of others. The former element was foiled by McClane's intervention on the roof, leading Hans to activate the explosives prematurely, while the latter was stopped by Argyle when he t-boned the ambulance and punched Theo unconscious in the parking garage.
But what would cause the authorities to think that the terrorists would be on the roof when it blew up? They could have been on the bottom floor for all they knew. I remember the movie quite well, but may have missed a line that clarifies to the authorities that they were going to be on or close to the roof.
As Hans says: "When they touch down, we’ll blow the roof. They’ll spend a month sifting through rubble, and by the time they figure out what went wrong, we’ll be sitting on a beach, earning twenty percent." I don't think Hans was expecting the authorities to assume they were all dead forever, just cause enough carnage and confusion that they can escape. The FBI might think they were dead, or if nothing else not know where they went. The bodies McClane had left behind might even help muddy the waters. They could then escape to a non-extradition country and live in peace, no matter if anyone figured out they were alive or not.
Shortly after he kills Ellis, Hans radios Deputy Chief of police Dwayne T. Robison. He tells him to get his "comrades" released. He lists off several actual terrorists, then tells Dwayne that after those people are released, the hostages will be taken to the roof and accompany them by helicopter to the airport. Later, Agent Johnson of the FBI tells Hans that his demands have been met and that helicopters are en route as requested. That's why the Feds think the bad guys will be on the roof.
Question: When Karl and Hans shoot all the glass in the office, why didn't they follow the blood trail left by John and then kill him?
Answer: Karl wanted too, but Hans said, "Forget him, we got what we wanted." The detonator caps, to blow up the of the top building. They were on a tight schedule, to use the explosion, killing the hostages, leaving the police to think the terrorists were killed. Despite everything McClane did, they still thought of him as an annoying distraction, not worth their effort to find him.
Question: John McClane's wife calls herself "Miss Gennero." Later in the movie her children are being interviewed on television - but how could Hans Gruber possibly know these are her children? And how does he connect her and the surname "McClane"?
Answer: He sees her reaction to seeing them on the news; he can tell she knows them, and from this, it's not a big leap to the conclusion that they are her children. Then, the reporter says to her daughter, "Your mommy and daddy...", but Holly has claimed to be single and her husband is not among the party guests, so he further deduces that she must be married to John McClane, or if nothing else that she's avoided mentioning her husband for a reason. A look at the downturned photograph on her desk confirms his suspicion.
Question: When Hans is interrogating Takagi, why would he remove a silencer to fire the weapon indoors without hearing protection? Wouldn't it be more menacing to put a silencer on in that situation?
Answer: I think he's just subtly showing Takagi that he's in control of the situation - there's no need to hide behind a silencer, which they were using earlier. They've taken over and can do whatever they want, including loudly executing people. It's a very subtle power-play.
Answer: They used guns with silencers to access the building and take control swiftly and quietly. Now that they no longer need to do that he takes off the silencer. A silencer affects the gun's accuracy. It is also highly likely he wanted the people in the other room to hear the shot.
Question: When John sees a group of SWAT guys head to the building, why does he react by saying, "No, no, no!" Wasn't having the police come to help exactly what he wanted?
Answer: As you may have noticed in the immediate run-up to this, he has been trying to warn them against taking direct action. He has tried to tell them that they are fighting heavily armed and highly trained terrorists who are well-prepared to handle a small group of policemen overtly entering through the front door. So, he was saying that because he knew the SWAT men were about to get hurt, or worse, in their idiotic attempt to, as Dep. Chief Dwayne puts it, "kick ass."
Question: Can someone explain what the one Johnson agent meant to the other one when he said "it's like Saigon, ain't it slick?"
Answer: I don't remember the exact quote, verbatim, but using your wording, the proper punctuation would be "It's like Saigon! Ain't it, Slick?" The older Johnson is referring to Army Helo Ops in Vietnam. He's calling the younger Johnson "Slick", as a nickname. I believe the younger's response was something like "I was just a kid then" or something similar.
The younger one says "I was in junior high, dickhead". :-) Clearly not holding the older Johnson in especially high regard, or keen to make it clear he's not as old.
Answer: The elder Agent Johnson is a Viet Nam vet who excitedly says, "It's just like f***in' Saigon, eh Slick? The younger Johnson mockingly responds, "I was in Junior High, dickhead!" meaning he was too young to have served in that war. The older Johnson is comparing shooting at the terrorists (or just John McClane) atop the Nakatomi Tower to killing enemy soldiers from a helicopter in Nam. He is macho, has lost objectivity about the hostage situation, and is treating it like an arcade game. As pointed out in another answer, "Slick" is just a nickname, like calling someone "Dude."
Answer: "Like Saigon" could mean that under the circumstances, they were not likely to win or be successful in what they were trying to accomplish. Largely in the 1960s, the U.S. military was stationed in Saigon. While there, parts of the city were ruined or demolished by fighting. There was a lot of destruction in the Die Hard movie, and the situation seemed dire.
Question: In one scene, McLane turns on an electric saw to distract the terrorists. When he's having no luck finding shoes that fit, why didn't he just use the saw to cut the toes off a pair of shoes?
Answer: There's no answer, though it would have been dangerous for McClane to go back and use a noisy saw. The dead guy's cohorts might be around and/or are looking for him and could hear the noise. McClane also had to move quickly to get the body into the elevator and down to the party floor, so he could gain info about the other terrorists. The shoes may also have been too tight and narrow as well as too short, making them unusable.
Answer: Karl understood what Hans was saying in German. He hesitated because he was puzzled by the request, probably unaware, unlike Hans, that John would have to run through shattered glass while barefooted. Hans repeating it in English is merely a plot device so that the audience understands what he's saying without subtitles being used and it emphasizes Hans' urgency.
raywest ★
My interpretation is that when Hans said it in German, he said it too quietly for Karl to hear. When Hans repeated his command in English, he said it louder.