The two- and three-panel screen presentations seen through much of the movie were innovations born of necessity on the part of its creators and film editor Martin Scorsese. With so much footage shot and the studio's unwillingness to expand the length of the released movie's running time, it was decided that a way must be found to maximize the amount of footage that could be used. Because of the wide-screen aspect of the release, it was realized that the multi-panel format could be used most effectively to not only include as much film footage as possible, but to also have concert footage and crowd reaction shots together on the same screen. The filmmakers believed it was important to show the viewing public just what a monumental event the Woodstock festival had unintentionally become. This method also allowed them to show many behind-the-scene activities that reflected all the hard work put in by the production staff and crew, another important detail that the concert's producers thought was very important for the public to see as they always had contended that without the efforts of the entire production staff, this event easily could have degenerated into a disaster.
The Who's performance was interrupted by Yippie leader Abbie Hoffman. Hoffman ran onstage to make a speech about the recent marijuana arrest of radical John Sinclair. As Hoffman was shouting about Sinclair and his displeasure about the festival, Pete Townshend kicked him off the stage.
Richie Havens' song "Freedom" was totally improvised. He was called for so many encores that he ran out of songs to sing, so he just picked up his guitar and started singing "Freedom".
Crosby Stills Nash & Young almost didn't perform at the festival. The helicopter that Graham Nash and the group's bassist, Greg Reeves, were on was less than 25 feet off the ground when the tail rotor failed and it began to spin. The helicopter almost crashed and Nash and Reeves were almost killed when it not only made a hard landing, but just missed some high-tension power lines.
When the promoters were negotiating to get Grateful Dead to perform at the festival, Bill Graham, who was managing the band at the time, insisted that the promoters include one of two other acts he managed on the bill. Michael Lang listened to recordings of both bands and liked them so much that he couldn't decide which one to put on the bill and wound up flipping a coin; the winner would be booked. The losing band was It's a Beautiful Day. The band that won the flip was Santana, which would achieve superstardom on the basis of their appearances at both the festival and in the movie.