Trivia: Nakatomi Plaza, the setting of the film, is actually Fox Headquarters in Los Angeles.
Trivia: For the shot where Hans Gruber falls from the top of the building, Alan Rickman was dropped by a stuntman from a 20-foot high model onto an air bag. To get the right reaction, the stunt man dropped Rickman on the count of two instead of three. Rickman said "That sounded like fun and so I decided to do it, I thought they were a bit surprised that I said I would and I was surrounded by people saying, 'You're mad, you're mad!' But no, it was fun. And it was the last shot, so if I'd broken my neck, they'd still have a movie."
Trivia: At the end, Karl emerges from the building and tries to kill McClane, only to be gunned down by Powell. The triumphant music which swells as Powell shoots him is from the "Aliens" score--it plays at the end of that movie when Bishop reappears in the dropship to save Ripley and Newt, after they think he's abandoned them.
Trivia: Die Hard and Die Hard 2 are based on books by separate authors, "Nothing Lasts Forever" by Roderick Thorp and "58 Minutes" by Walter Wager, which share none of the same characters. In both books, it is the hero's daughter that is in peril rather than his wife, and the hero is also more trusted by the authorities than McClane. (In "Nothing Lasts Forever," he tosses his wallet out the window so the police on the ground know he's a cop.).
Trivia: In the German version, all German terrorists received Anglicized names, and their background was altered as well. This was due to terrorist activities in Germany - the kidnapping of an airplane in Landshut (1977) and the activities of the Rote-Armee-Faktion ('Red Army Faction') in the Seventies; the German producers evidently felt uncomfortable about the idea of having German terrorists appear in foreign movies also.
Trivia: The terrorists show up at Nakatomi Plaza in a truck marked "Pacific Courier" (except Karl and Theo, who arrive by car). This fictional company name also appears on the side of the plane the bus crashes into at the end of "Speed." Jan de Bont, who directed "Speed," was DP on "Die Hard."
Trivia: All the terrorists are wearing the same make of watch, a fact that was cut from the movie. On leaving the truck at the start they synchronised them, and after killing some of the men, McClane noticed the matching watches. This is primarily what gave away "Bill Clay" as being a terrorist - McClane, already suspicious, noticed the brand of watch he was wearing. These references were cut because of a change to the script. The ambulance being used at the end was a late addition, however the synchronisation scene took place in the truck, where there was blatantly no ambulance (as noted in the mistake section). As such they cut that shot as short as possible, banking on audiences not registering the lack of ambulance, but the price was having to lose all reference to the watches.
Trivia: The password cracked to enter the safe is Akagi / Red Castle, the name of an aircraft carrier which seemingly Takagi's grandfather served on. It fought in the Battle of Midway, under the command of Vice Admiral Nagumo. James Shigeta, who played Takagi in this film, also played Nagumo in the 1976 film Midway.