Music (Score)
Oh, was there music in this movie? We didn't notice.
This movie is the score; the score is the movie. Without the band's music, they're just three guys in Spandex screaming at crowds of strangers. That will land you in the county jail, nine times out of ten.
Nearly every song in the film was written and composed by whichever actors performed it. Christopher Guest, Michael McKean, Harry Shearer, and even Rob Reiner were involved in the process. Which says a lot about how talented these folks are. The songs themselves may be ridiculous, but the musicality is actually impressive. There are Stevie Wonder songs that don't get stuck in our head as much as "Hell Hole."
And no, they didn't bring in incredible, accomplished musicians and singers to dub anything over during post-production. Every member of Tap is one hundred percent legit. They did their own playing, and their own singing. Which, once again, doesn't hurt when it comes to trying to present an authentic-looking product.
However, no—the drummer didn't actually spontaneously combust. There was at least a little Hollywood going on here.