Godfrey Reggio was hooked on Philip Glass doing the music. He approached Glass through a mutual friend, and Glass replied, "I don't do film music." Reggio persisted, and finally the friend told Glass that the tenacious guy was not going to go away without at least an audience. Glass relented, though he still insisted he wasn't doing the music. Reggio put together a photo montage with Glass' music as the soundtrack, which he presented to Glass at a private screening in New York. Immediately following the screening, Glass agreed to score the film.
It took almost 6 years to make the film.
One shot of a mountain range was provided by MacGillivray-Freeman Films; the shot was leftover footage from O Iluminado (1980). Another film to use leftover footage from the same very stock was Blade Runner: O Caçador de Andróides (1982) which famously included some in theatrical ending.
Scoring for the film took over 3 years as it was a continually evolving process.
Philip Glass divided the film into 12 different sections and wrote music for each. However, once Godfrey Reggio heard the music, he completely reassembled the film, cutting to the feel of the music and not its structure.