Jason Segel actually got naked-dumped in real life.
IRL, though, Segel actually put clothes on midway through the breakup...which was equally awkward.
Jason Segel didn't tell his family about the nude scene; his mother cried in the theater.
Although Segel did his own nudity, those aren't actually Mila Kunis' boobs in the photo.
Years before Forgetting Sarah Marshall, Segel had actually written a Dracula musical that he wanted to perform, with puppets.
Later, Segel jokingly suggested they use the musical in the movie, but Judd Apatow liked the idea.
Russell Brand hadn't even read the script when he came in to audition.
Based on Brand's attitude, Segel completely re-wrote the character of Aldous Snow.
That wasn't the only strange coincidence: Bell's show, Veronica Mars, was cancelled the day before Bell shot the scene where Sarah finds out her show is cancelled.
Segel got the idea for Crime Scene: Scene of the Crime after he guest-starred on CSI.
Mila Kunis auditioned for the lead in Knocked Up, but didn't get the part.
Segel wrote the song "Inside of You" as an attempt at "the worst song your ex-girlfriend's new boyfriend could sing in front of you."
Actual women named Sarah Marshall were upset by the billboards, which had mean messages addressed to Sarah's character.
Segel's breakup with Freaks & Geeks co-star Linda Cardellini partially inspired the movie.
The puppets for the Dracula musical were made by Jim Henson's Creature Shop.