According to a interview in Rolling Stone, director Brett Morgan planned on including Nirvana drummer Dave Grohl in the film, but Grohl was busy filming Sonic Highways. By the time Grohl was available Morgan was satisfied with his cut of the film and decided not to include him.
According to a Vanity Fair interview with Director Brett Morgen, after Frances Bean Cobain saw the film at it's Sundance premiere, Morgen escorted her back to her car. Before leaving, Cobain embraced Morgen and said, "You made the film I wanted to see."
The name Fecal Matter is seen briefly. This was the original name of Nirvana before it was known as Nirvana