Several rock stars have commented on what an uncannily accurate spoof of the rock and heavy metal world this film was. Ozzy Osbourne said that when he first watched the film, he was the only person who wasn't laughing; he thought it was a real documentary. U2 guitarist The Edge said about this movie: "I didn't laugh, I wept. It was so close to the truth." Marillion had five drummers in the space of a year between their first and second album, which guitarist Steve Rothery later admitted was "like Spinal Tap".
In his memoir "Father Joe", Tony Hendra admits that he attempted suicide the night before the first day of filming. He credits the joy he experienced in making the film with bringing him back from his depression.
Thirty-seven different people have been in the band over the years. Excluding the two original members, one keyboard player, and the original and current bass players, that means the band has had 32 different drummers who inexplicably died.
As the film was improvised by all the performers, Rob Reiner, Christopher Guest, Michael McKean, and Harry Shearer went to the Writers' Guild hoping to give proper credit to everyone. The Board of Directors voted 15 to none that the credits should stay as it was including only the four of them.
Director Rob Reiner asked Mark Knopfler, the frontman and guitarist of Dire Straits, to compose the score to The Princess Bride (1987). Knopfler agreed, under the condition that the cap Reiner wore in this film appeared in the movie. Reiner got a replica cap and put it in the boy's present-day bedroom.
In Norway, the film was released direct to video over two years later. The title was changed to "Help! We are in the Pop Business!" ("Hjelp! Vi er i popbransjen!"), a spin on the Norwegian title for "Airplane!" (1980), "Help! We are Flying!" ("Hjelp! Vi flyr!"). The poster showed a guitar with a knot in it, similar to the airplane on the "Airplane!" poster. Throughout the film, an on-screen disclaimer reminds the audience that the band is fake.
When Nigel describes the sustain on his Les Paul guitar, he says he could "go out and get a bite" and "you'll still be hearing that one." Les Paul described the sustain on one of his own guitars: "You could go out and eat and come back and the note would still be sounding."
Contrary to popular rumor, the "too small Stonehenge" disaster is not a parody of Black Sabbath's over-sized Stonehenge sets from the Born Again tour. The Stonehenge Spinal Tap scene existed as early as 1982, when the film was a 20-minute short. Black Sabbath didn't begin using their Stonehenge sets until 1983. The Stonehenge scene was likely inspired by the setup for Led Zeppelin's final two U.S. concerts, at the Oakland Coliseum, July 23 and 24, 1977. The stage was framed by a large, Stonehenge-like monolith. Additional Stonehenge models appeared on the stage and large banners to either side of the stage featured images of Stonehenge. The concerts are infamous because several members of Led Zeppelin's entourage beat up a local crew member backstage after the first day's performance.
Nigel talks with DiBergi about being influenced by the masters, including Wolfgang Amadeus Mozart and Johann Sebastian Bach. During their performance of "Heavy Duty", Nigel's solo (which he plays while standing on the drum riser) is a tribute to Luigi Boccherini's "Minuet from String Quintet in E major, G.275".
In the course of the film, Spinal Tap has four different drummers: John "Stumpy" Pepys, Eric "Stumpy Joe" Childs, Mick Shrimpton, and Joe "Mama" Besser. The names were inspired by the four different men who played the third Stooge in The Three Stooges films: Curly Howard, Joe DeRita, Shemp Howard, and Joe Besser.
Before the first song, an announcer introduces the band by saying "Ladies and gentlemen, direct from Hell, Spinal Tap." That's is a play on Venom's intro tape from the early 1980s: "Now, from the very depths of Hell, Venom!"
Although they portray Englishmen, none of the three lead actors are actually English. Christopher Guest comes very close, though, as he is the 5th Baron Haden-Guest by right of hereditary British peerage.
Marillion's 1987 UK top ten single "Incommunicado" includes the line "currently residing in the where are they now file", which was taken from the film. The song was written from the point of view of a rock star struggling with the lifestyle and the pressures of success.
Spinal Tap are infamous for problems with their Stonehenge props. The most famous incident comes from the film, in which the prop is undersized and nearly trampled by a dwarf. On their live tour in support of Break Like The Wind, a package delivery man brings a package with an even smaller model. In The Return of Spinal Tap, the prop is far too large, and the stage crew makes every effort to cram it through the small doorway, and fails. When they performed at Live Aid (1985), the prop, signed by all the other performers, was the right size, but the "columns" were lowered without the top crossing piece, and subsequently removed from the stage. The top piece eventually lowered with nothing to land on.
Marty Di Bergi wears two different US Navy caps - one in the film and one in 'Catching up with Marty Di Bergi' in the Special Features on the DVD release. In the film, the cap appears to read USS Coral Sea OV-48. This should be USS Coral Sea CV-43. The USS Coral Sea was an aircraft carrier in the US Navy 1946-90, the second ship to bear that name. In the special features, the cap is from the USS Wadsworth FG-9, a guided missile frigate in the US Navy from 1978-2002. The Wadsworth was transferred to Poland in 2002 and renamed the General Tadeusz Kosciuszko.
Lt. Bob Hookstratten, who welcomes the band to Lindbergh Air Force Base in Seattle to play at its monthly "at-ease weekend", was inspired by prominent sports and entertainment attorney Ed Hookstratten.
R.J. Parnell was cast as Shrimpton after he went through all the failed bands he had been with during his audition. Ironically, Parnell would also be the drummer on one of the biggest hits in the country the year the movie was filmed: Toni Basil's "Mickey."