The trike that Johnny Knoxville uses in the film is the original bike that Phil Kaufman used in 1973.
Gram Parsons died in Room 8 at the Joshua Tree Inn, which is the room Larry and Phil find Mr. Parsons in at the end of the film when they explain their reasons for kidnapping Gram's body. Room 8 is known as Gram Parsons's Room at the Joshua Tree Inn Bed and Breakfast and can be rented for overnight stays.
The tattoos that Johnny Knoxville has in the film are a mixture of real ones and ones made for the movie. For instance, the tattoo of the word "Madison" (the name of Knoxville's real-life daughter) over his heart is real but the bigger ones on his arm are not.
At the end of the film outside the police station: the sequence showing one civilian and a cop going into the station and one civilian coming out was filmed twice, once in close-up and then again from across the street with Kaufman and The Hippy discussing turning themselves in.
Phil Kaufman: at the end of the movie where he is led down the steps of the local police station protesting his innocence.