Money, Dear Boy: Harvey's appearances on Late Night With David Letterman were always based on Letterman paying him to come into New York City, even if Harvey ended up being scheduled off. He even turned down a chance to be on Oprah because they wouldn't pay him to do it. However, there is a justification: Unlike their other guests, Harvey is not rich, and had a day job that he would need to take days off from to do the shows.
Name's the Same: "The Harvey Pekar Name Story," which was also adapted for the movie: Harvey tells about seeing two other Harvey Pekars in the Cleveland phone book, which baffles him, since the name "Harvey Pekar" should be kind of rare.
Write Who You Know: Pekar's real-life friend Toby Radloff was written into the comic at one point.