John McTiernan's 1988 film, Die Hard is considered one of the greatest action movies ever made and also one of the best Christmas films as well (even though Bruce Willis has confirmed his belief that it is not a Christmas film, many regard this film as essential Christmas viewing).
In equal parts an action film combined with a heist movie and a disaster flick, Die Hard has captured imaginations and created enjoyment around the world as audiences follow Bruce Willis's everyday hero, John McClane in his bid to be reunited with his estranged wife in the Yuletide Season, following a Christmas party that, well, could have gone much better.
The film made a star out of Willis practically overnight and spawned a successful franchise that may or may not still be continuing (Willis does not look like he's ready to give up his favourite onscreen character anytime soon, whilst rumours of a prequel television series have been circulating for some years).
Importantly, it broke away from the 1980s trend of throwing beefcake stuntmen types such as Arnold Schwarzenegger and Sylvester Stallone into leading roles, instead giving viewers the opportunity to see Willis's everyday man - an on-edge cop - racing around a high rise building that, for all intents and purposes, seemed ready to collapse around him.
Like any great film, however, there is plenty about Die Hard that can easily be missed; this list explores 20 things that often go unnoticed.