Actor Phillip Seymour Hoffman completed filming for his role of Lester Bangs in four days. He had the flu the entire time. (Source.)

Patrick Fugit, who played William, actually had a massive crush on Kate Hudson—who played Penny Lane—during production. When Penny asks William if he wants to go to Morocco with her, Patrick actually steps out of character, asking Kate to repeat her line. "Yes!… Ask me again." (Source.)

In real life, Cameron Crowe's mother and sister did not speak for years before the completion of Almost Famous. Crowe explained to Rolling Stone that "in his wildest dreams," he hoped the movie would help them reopen communication. Sure enough, it did. (Source.)