Both contain the main characters turning into the real people at the end - Hopkins playing Nixon walking out of the White House cuts to real footage of Richard Nixon walking out of the White House, and Paul Giamatti walking down the sidewalk at the end cuts to footage of Harvey Pekar walking down that same sidewalk.
poster at movie theater
Paris refers to one of Rory's classmates as "Toby from American Splendor."
In Raise Your Voice, Paul has an American Splendor poster on his bedroom door.
Mentioned in the Limo Ride skit
bottom half of poster visible in video store
Mentioned by Richard when talking to Lenny about Hope Davis.
footage used for the film
Movie describes how Harvey Pekar's friend Toby Radloff became a "Genuine Nerd" correspondent for "MTV News" incorporating actual footage from at least one of the real Toby Radloff's "MTV News" appearances.
Footage is shown when Ellen discusses movie adaptations of graphic novels