Simon Pegg and Nick Frost, the inspired British duo who spoofed horror movies in Shaun of the Dead and cop thrillers in Hot Fuzz, star as sci-fi fanboys who arrive in the U.S. for a comic-book convention and, piloting their RV through Area 51, pick up an escaped space alien with the voice of Seth Rogen. The script is a veritable cosmos of Spielberg in-jokes, but the writer-stars also make room for some vicious and decidedly English digs at red-state shit-kickers and Christian fundamentalists. This is the first big Hollywood feature for Pegg and Frost, and their two prior successes seem to have functioned as a supermagnet, attracting not only the skilled comedy director Greg Mottola (Superbad, Adventureland) but a supporting cast that could sustain two or three movies on its own (Kristen Wiig, Jane Lynch, Jeffrey Tambor, Jason Bateman, Bill Hader, Blythe Danner, Sigourney Weaver).