Jimi Hendrix's estate refused to grant music rights unless they were allowed full participation in the film's production. For that reason, all of the Hendrix songs in the film are covers. At the time the movie is set, 1966-67, Hendrix had three top 10 singles in the UK ("Hey Joe," "Purple Haze," and "The Wind Cries Mary") and a hit album ("Are You Experienced").
André Benjamin is actually a mediocre guitar player. In an interview with NME he said: "One of the hardest parts [was] I'm a right-hand guitar player. I'm a horrible right-hand guitar player. I wouldn't even call myself a guitar player; I just pick it up and fiddle with it every now and then. When it came time to do the left-hand thing, it's almost like walking backwards and making walking backwards look normal."
The trivia item below may give away important plot points.
In one shot, Jimi Hendrix requests to jam with Eric Clapton during a Cream concert. Hendrix played the blues song 'Killing Floor', leaving Clapton shocked at his talent. Ginger Baker later said in an interview about that scene, "When I met Eric, I knew he was a great guitar player, but when I met Hendrix, I knew he was like a force of nature."