I think the thread has strayed from the key question:
>Are there other films
>that plug particular social/political agendas and/or the
>works with elements of setting and such?<
But in part it may be because of that troublesome word "author"--the whole
knotty question of who is the auteur of a movie. For example, in the heyday
of the studio system, you often found plugs for the studio's stars in films
in which they didn't appear: e.g., MGM rising star Judy Garland's "You Made
Me Love You" serenade to MGM superstar Clark Gable's photograph in "Broadway
Melody of 1938," or the Hope/Crosby cameos in each other's films for
And if you consider stars as auteurs, there's no more self-referential movie
than "Sunset Boulevard," in which the character of Norma Desmond is built up
out of pieces of Gloria Swanson's life: the film clip from "Queen Kelly," the
casting of Erich von Stroheim and Cecil B. DeMille as Norma's
ex-directors--and especially DeMille's greeting Norma as "young fellow," his
pet name for Gloria.
And as far as in-joke plugs go, one of the best I can think of is Barbra
Streisand's telling Ryan O'Neal "Love means never having to say you're sorry"
at the end of "What's Up, Doc?"