Trivia: Mentioned in the DVD commentary, is that the Tunnel (used to trap McClane and Farrel with traffic from both directions in DC) was an open tunnel and they had to shoot at night because they could not afford to cover it with their production budget. This is obvious from most of the shots pointed to the room where you can see a "break into night" opening. (00:42:55)
Trivia: The only film in the franchise to not receive an R-rating in the US. 20th Century Fox pushed for the film to have a lighter PG-13 rating. Star Bruce Willis and director Len Wiseman chose to simply film the movie that they wanted to make without worrying about the rating during filming (as so not to negatively influence the film's production or feel they were holding back too much), leaving the necessary editing for the PG-13 rating for post-production editing. An unrated version of the film was released later on DVD and Blu-Ray that retains much of the violence and profanity that was cut for the PG-13 rating.
Trivia: Bruce Willis' stunt double, Larry Rippenkroeger, nearly died in the scene when McClane and Farrell are escaping the apartment. Due to rain the previous evening, the fire escape was slippery, requiring the use of stunt doubles. However, Willis' double mistepped and fell off the fire escape, falling 25 feet. Willis himself paid for the hospital bills and visited Rippenkroeger several times.
Trivia: The film's overseas title in many countries is "Die Hard 4.0" - the "point-oh" in the title being a reference to how software often goes through different variations and updates. (1.0, 2.0, 2.1, etc.) Series star Bruce Willis has stated that although the film was released as "Live Free or Die Hard" in the US, he far prefers the "Die Hard 4.0" title, as it's clearer in indicating that the film is a "Die Hard" movie through and through.