The Hangover/Trivia

Part 1:

 * Actor Allusion: The use of Kanye West's "Can't Tell Me Nothing" in the first film may be in reference to Zach Galifianakis's earlier music video for the song.
 * Hey, It's That Guy!: Rob Riggle, a former cast member of Saturday Night Live and The Daily Show plays the police officer who uses Phil, Alan, and Stu in his taser demonstration.
 * Mr. Chow is played by Ken Jeong, who plays the crazy Spanish teacher Señor Ben Chang on the NBC sitcom Community.
 * Indeed, since nobody really knew the actor's name at the time, promos for Community billed him as "That guy from The Hangover!"
 * Bradley Cooper was previously best-known as the Jerkass fiance from Wedding Crashers.
 * And Will in Alias.
 * Riley from National Treasure is now the thing people are searching for!
 * Andy from The Office married a whore!
 * Star-Making Role: Basically all three leads. Zack Galifianakis got the most immediate attention; Bradley Cooper got equal billing with Liam Neeson in the film version of The a Team; Ed Helms has a number of lead comic roles in production and received an increased role on The Office.
 * Additionally counted as a Breakout Role for Ken Jeong, who saw himself cast as a supporting player in a number of major Hollywood films immediately afterward. He also ended up becoming a main cast member on Community.
 * What Could Have Been: Lindsay Lohan was originally supposed to play Jade, but she turned down the role because she didn't like the script, and she didn't think the film would be that successful. Despite the film's huge box-office success, she went on record saying she didn't regret her decision.
 * Written-In Infirmity: Ed Helms (Stu) actually does have a missing tooth in real life. He had his prosthetic tooth pulled out for the movie.

Part 2:

 * What Could Have Been: Mel Gibson was originally supposed to have a cameo in the sequel as a tattoo artist, but Word of God states that this fell through after cast & crew objected to his involvement. The role then went to Cooper's The A-Team co-star Liam Neeson was then cast in the role, and the scene was filmed, until the scene required re-shooting with new expository dialogue after some editing. Neeson was unavailable for the re-shoot due to scheduling conflicts, so the entire scene was shot with Nick Cassavetes in the role.