John Cusack and the screenwriters wrote the script with Jack Black in mind for the role of Barry. He nearly turned the role down, but reconsidered.
John Cusack originally wanted Bob Dylan for the Bruce Springsteen cameo part, but Dylan was unavailable.
Stevie Wonder originally performed the closing track "I Believe" before Art Garfunkel and Peter Frampton covered it. All three are artists that Rob, Dick, and Barry ridicule in the movie.
Nick Hornby had no problem with the film version relocating the action from London to Chicago, as he felt that the book was about a lot more than just geography.
During an October 2019 AV Club interview with Tim Robbins, he mentioned that he agreed to take the small roles in High Fidelity and Anchorman (even though he knew he would be paid very little for them) because they promised to make him a custom wig for each of the roles, both of which he got to keep after filming ended. Robbins said that he still owns both wigs as of 2019, and he often uses them in Halloween costumes.