When Sandy is following Diana down the highway, there is a quick glimpse of the speedometer of her car as she accelerates. The car says it is "Tue 23 Feb." However, based on the photo IDs, Sandy's birth date is 18 May 1974. The movie takes place in May just after his birthday, based on his family celebrating his birthday near the beginning of the movie.
"Bad Girls" by M.I.A. The complete list of songs heard in the movie can be found here with their corresponding scene descriptions.
What are the differences between the Theatrical Version and the Unrated Version?
The DVD/BD releases contain a longer Unrated Cut that adds almost 9 minutes of material. The clear conclusion here is that the majority of those scenes feel like they were cut out of the theatrical version because they simply weren't needed or slowing down the events. Typical "unrated" material that could've been too risky for the "R"-rated theatrical version is nowhere in sight. A detailed comparison between both versions with pictures can be found here.