There are many popular culture, science fiction, and comic book references in this movie. During the movie, the two main characters wear T-shirts featuring: Flash from DC Comics, Ming the Merciless (Flash Gordon), Star Wars: Episode V - The Empire Strikes Back (1980), "Invincible" (by Robert Kirkman), and "Eightball" (by Daniel Clowes). They attend the San Diego Comic Convention twice (with many comic and science fiction references). Other references include a lot of Steven Spielberg projects (E.T. the Extra-Terrestrial (1982), Close Encounters of the Third Kind (1977), Indiana Jones and the Temple of Doom (1984), et cetera.) Steven does lend his voice to one scene. Other homages include: the Alien franchise (Sigourney Weaver), Predator (1987), Back to the Future (1985), The X-Files (1993), Star Trek (Simon Pegg stars in the recent movies), and Star Wars. Supporting cast member, Bill Hader, is a huge comic book fan. He teamed up with Saturday Night Live (1975) cast member Seth Meyers and Kevin Maguire for a one-shot Spider-Man comic book. Even the music soundtrack has many inside references, such as John Williams, The B-52's, and David Bowie. One main scene, takes place in a comic book store with tons of references to comics (Hellboy) and science fiction (Master Yoda).