Originally intended as a vehicle for Will Ferrell. He received an Executive Producer credit. The Lonely Island re-wrote the script, because it couldn't be read without Ferrell in mind, and Schaffer didn't want the movie to be an impression of Ferrell.
The "Cool Beans" song was originally pulled by Akiva Schaffer, but the scene was edited by Samberg and Taccone, and eventually Schaffer reinserted the scene in the last test screening, where it received high remarks from the audience, with some saying it was one of their favorite parts of the film.
Shares the same basic plot line as Dirty Work (1998), which also starred then-current cast members of Saturday Night Live (1975). Both films are centered around an unsuccessful young man attempting to raise fifty thousand dollars for his father, a cranky ex-boxer, to have a heart transplant.
All of Andy Samberg's (Rod's) stunt doubles had prosthetic noses, to make them seem as big as Andy's. Jorma Taccone (Kevin) and Akiva Schaffer played a joke on Samberg, by requesting the prosthetics be larger than his own nose, so he would feel insecure.
During filming the scene with Denise ("You look pretty" "What did you say?" "Uh, I said you look s****y. Goodnight, Denise!") it was raining during the shots of Andy Samberg, and the rain had to be digitally removed.
In the commentary, the guys say they heard of John Farnham, because he had some songs in Rad (1986). They used the song "You're the Voice" by Farnham in the riot scene. Rad (1986) was a movie about a young man's journey to win a BMX race called Helltrack.
Prior to the film's release, The Lonely Island (comprised of Samberg, Taccone, and Schaffer) promoted the film with interstitials during Comedy Central movie marathons. In the promos, the trio attempted to convince viewers that Hot Rod was the story of a sex-offender, "he does stunts to raise money to sex-offend."
Brittany Tiplady, who plays Maggie, Dave's (Bill Hader's) sister, had about a week left before she got her braces off, and she was excited to remove them in time for the movie, but Akiva Schaffer jokingly made her film her scene before she got her braces off.
Akiva Schaffer's mother makes a cameo as an extra in two scenes. She's pelted with flyers by Richardson as she walks to her van, and later, she is shown sitting next to him during the screening of Rod's video.
In the scene with Rod (Samberg) riding his bike to his date with Cathy (Britt Irvin) and singing "Ohhh when you're going on a date, and you put on a shirt! And you ride your bike to the daaaaate," was improvised by Andy Samberg.
There are a few subtle references to professional wrestling in the movie, including two of the characters wearing WWE t-shirts. In one scene, Rod wears a Hulk Hogan "Hulkamania" t-shirt, and in another, Dave wears a "Stone Cold" Steve Austin t-shirt.
The trivia item below may give away important plot points.
The original movie poster was a picture of Andy Samberg standing on a hilltop and taking a bow in front of his moped, much similar to the after-credits sequence. This poster was preferred by Akiva Schaffer, Adam Samberg, and Jorma Taccone. The studio wanted the movie's official poster to be the one featuring the main characters.