Knoxville was actually cast as the San Francisco Hobo, but could not accept due to conflicting schedules.
Had been set to play the son who arrives home for the holidays with his uptight girlfriend.
Knoxville was going to play Harry Lockhart before being replaced by Robert Downey Jr. prior to filming.
Actor who got the part: Robert Downey Jr.
Did you know that Johnny Knoxville was not the only choice for this movie? (click to learn more)