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 any way.
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.
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).
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.
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.
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.
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."
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.
The trivia item below may give away important plot points.
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".