Trivia: Ewan McGregor has a cameo in this film after he turned up on set to visit Charlize Theron and Liam Neeson. Charlize Theron asked him if he wanted to do it for fun, somewhat blindsiding Seth MacFarlane, who quickly got on board, not least as McGregor already had suitable facial hair as he was filming Jane Got a Gun at the time. The whole scene was done off the cuff, and he is uncredited. He's the man at the fair who gets challenged by Seth MacFarlane to explain why he's laughing and says "I don't know. He was laughing."
Trivia: Although it sounds made up to fit the plot of the movie, the song "If You've Only Got a Moustache" was a real song from the 1860's. It was written by Stephen Foster (lyrics by George Cooper) who also wrote "Camptown Races" and "Oh! Susanna," although some of the lyrics were changed in the film. Foster (who is also brought up in a later scene) incidentally died at the age of 37 from a fall and fever, which also seems to fit the plot of the movie of so many random ways to die.