FAQ for
Live Free or Die Hard (2007) More at IMDbPro »

The most obvious answer is that the series has always been known for its hard-core action and profanity, and as such much of this has become characteristic of Bruce Willis' portrayal of John McClane. The phrase "Yippee ki yay, motherf*cker" became a catchphrase for the series (a calling card similar to Arnold's or James Bond's), and the fact that it has been edited out of "Die Hard 4" in part (a gunshot mutes the last word of the sentence) has further upset "die hard" fans of the series, who feel it is an essential part of the series. Other fans are simply upset because they feel it is an early indication that FOX is trying to promote this film to a wider, younger audience - turning it into a standard action thriller rather than a bare-bones, realistic action film as the first three were. The first three entries in the series were all rated R by the MPAA, and featured an average of 50 F-words per film.

Fortunate Son by Creedence Clearwater Revival. It is also played early in the film in a scene where John and Matt are driving and the band is mentioned by John.

The previous "Die Hard" films were rated "R" while this one was edited down to a "PG-13" rating which came as a surprise and shock to most people. Fox especially have had a record of re-releasing titles as Unrated/"R" rated cut DVD editions such as Alien Vs. Predator, Daredevil and Mr & Mrs Smith. Also, Justin Long has said in interviews that alternate takes were filmed in some scenes that would be held back for future use in a possible "R" rated or unrated version of the film. Further evidence for the possibility of an unrated Die Hard 4 DVD was the numerous moments when character's mouths moved but they didn't say anything, or they said something that doesn't match their mouth movements.

An Unrated DVD became available on November 20, 2007, either by itself or with a second disc of bonus features. The Blu-Ray releases of "Live Free or Die Hard" and the "Die Hard Collection" do not include the unrated version for reasons unknown.

The movie's title, "Live Free or Die Hard", is a reference to New Hampshire's State Motto "Live Free or Die". Since people outside the USA are even more unlikely to know anything about that motto or New Hampshire, "Die Hard 4.0" has been used for the rest of the world to relate to.

It should also be known that "Die Hard 4.0" was also one of the working titles for this movie.

I'm So Sick by Flyleaf

According to Soundtrack.net, the trailer music is as follows (note that some of the music comes from licensed trailer music producers only and may not be commercially available):

"Goth (Remix)" - 615 Music / Craig Sharmat, "Cycler" - RipTide Music, "War Zone" - audiomachine, "Rankle" - X-Ray Dog, "Adrenaline Surge" - Future World Music, "Suicide Mission" - Wild Whirled, "Ode to Joy" - Sorman Nystrom, "Full Throttle Part #2" - Static, "Hits, Swooshes and Rises" - Distortion Music.

Well, the most plausable answer is that the film was originally rated R, and they just toned it down by changing the lines so the film would be viewed by a much more wider audience. There is no reason to why the lip-sync is bad, just not very good editing.