Until this film, Meat Loaf had not sang in a movie since The Rocky Horror Picture Show (1975) because he wanted to be accepted in the industry as a serious actor. He even thought that his appearance in "The Pick of Destiny" would "ruin" him, but he took the role of JB's father anyway.
The guitar played by Satan in the "Beelzeboss" sequence is a custom Washburn guitar designed by Dimebag Darrell Abbott of Pantera, presented to him when sales of their "Far Beyond Driven" album reached 100,000 copies sold.
Upon entering the music store in search of the 'Pick Of Destiny', KG (Kyle Gass) is seen wearing a Trainwreck t-shirt. Trainwreck is a group in which Gass is a vocalist and guitarist (under the pseudonym Klip Calhoun). He also produced the group's 2004 live album.
In the master exploder scene there is a bar patron wearing a 'Great Alaska Bush Company' t-shirt, which is a world renowned strip club in Anchorage, Alaska, and one of Jack Black's favorite places to go when he visits the state.
Dave Grohl, who appears as Satan, also played Satan in the video for the Tenacious D song, "Tribute", which is also referenced in the film. Grohl also lent his talents to several songs on Tenacious D's self-titled CD.
The symbols on the neck of the guitar KG gives JB (from bottom to top) are: a pentagram (point down); a cross; the infinity symbol; a crescent moon and the Star of David (on the same fret); the yin-yang; the equation for Albert Einstein's theory of relativity; a cannabis leaf; and the Eye of Providence (eye inside a triangle). The headstock has a crown inscribed with the word "ROCK."
There are two references to other songs "Sasquatch" and "Tribute". Jack mentions in search of Sasquatch as being on TV. when in KG's home and on of the first lines of Sasquatch is "In search of Sasquatch - That was a kick ass In search of..." Tribute is referenced at the end when JB and KG can't remember the song they just sang, hence writing "Tribute" to tribute the song.
The car chase ends in front of Uncle Al's Seafood at the corner of First and Elm streets in Long Beach, CA. This is the same intersection where Riggs and Murtaugh blew up a gas station in Lethal Weapon 4 (1998).
Some scenes from the movie are actually rewritten from the original HBO tv show. The scene with JB and KG at the open Mic night is the most recognizable because the first episode of the original show starts off with tenacious D playing the song "History". The same actors are also used for Lee and the open mic host in both scenes and Lee is wearing the same tenacious D rocks shirt as he does in the episode back in the 90s.
In the Classic Rock room at the Rock & Roll History Museum, the mannequin on the right is a likeness to David Bowie persona Ziggy Stardust. The one on the left, judging by the scarfs wrapped around the microphone stand, is Steven Tyler of Aerosmith.
Being named after a native tribe, there are five towns in the US called Kickapoo in Louisiana, Kansas, Indiana, Wisconsin and Illinois, and 5 townships named Kickapoo in Louisiana, Illinois, Kansas, Oklahoma and North Dakota, however the Missouri town depicted in the film is considered to be a fictional one.
The car chase was filmed in and around downtown Long Beach, California. Major portions were shot on Shoreline Drive and the Queensway Bridge, where the final showdown in Kiss Kiss Bang Bang (2005) takes place.
One of two films in which Troy Gentile plays the childhood version of Jack Black's character. The first came earlier in 2006, when he portrayed the young version of Nacho in the Paramount Pictures family comedy Nacho Libre.
The film has multiple references to Tenacious D's first album "Tenacious D" (2001). Ronnie James Dio makes an appearance in the film which is possibly a reference to their song "Dio", after they have defeated the devil in a rock off they start trying to re-record the song they performed in the rock off by claiming it was "the greatest song ever made" yet not being able to remember it, this is obviously a reference to their biggest hit "Tribute". During the final showdown, they mention that they will rock the devil's socks off, this is quite possibly a reference to their song "Rock Your Socks Off".