The song that plays during the scene in which Neeco the tuxedo deliveryman tosses the guys' rented tuxedos into their speeding car is "Ride the Sky II" by Revolution Mother. Neeco is played by Mike Vallely, Revolution Mother's lead singer.
The digital camera that is found wedged 'in the backseat' of the car contains photos that explain many of their adventures over the night, including a few they had not been aware of, and are shown in the closing credits out of sequence. However, we see two sequences in the photo montage which occurred after they had dropped off the car, the visit to Mike Tyson's house (they were already in the police car by this point) and putting Doug on the roof (Doug was with them when they took the tiger, because he left his jacket behind and was seen on the Tyson security footage). Since the car had been abandoned before this point, these sequences should not have been on the camera.
When talking to Dr. Valsh in the hospital scene, Phil starts to write down "Best Little Chapel" on a piece of paper. He then asks Dr. Valsh where it is. After he tells Phil to get a map, the following shot of the piece of paper has nothing written on it and Phil rewrites "Best Little Chapel".
The following FAQ entries may contain spoilers. Only the biggest ones (if any) will be covered with spoiler tags. Spoiler tags have been used sparingly in order to make the page more readable.
Is "The Hangover" based on a book?
No. The Hangover is based on a screenplay co-written by American screenwriters Jon Lucas and Scott Moore.
What song is played as they come down the escalator?
The song is called 'Iko Iko' by The Belle Stars. It mimics the scene from Rain Man (1988) in which Dustin Hoffman and Tom Cruise descend on the escalator, although, in Rain Man, the song is used in the opening scene of the film. The rest of the songs and their corresponding scenes can be found here.