Rather gentler and more accessible than the other Pegg/Frost collaborations, this has them playing British sci-fi nerds Graeme and Clive, who go to San Diego ComicCon as a prelude to a roadtrip round UFO hot-spots, such as Area 51, Roswell and Apache Junction (I live less than 50 miles from the last-named and was completely baffled by this statement...). Their plans are derailed when they witness a car-crash. Attempting to help the victim, they discover it's actually an extra-terrestrial (Rogen), who had been working with the government since his craft crashed 60 years ago. Initially happy, he discovers they now have plans to extract his brain for further research, so makes a break for it. He enlists the help of Graeme and Clive to take him to his destination, where he'll be picked up by his people, but government agent Zoil (Bateman) is hot on their trail, apparently pursuing the federal designs on Paul's stem-cells and prepared to stop at nothing to track them down. There are also a couple of homophobic rednecks, who have mistaken our heroes for a gay couple.
It's gently amusing, without ever doing anything except the severely obvious, prodding moderate fun at science fiction and its fans, with the sharpest jabs being, surprisingly, aimed at intelligent design [though it doesn't address why intelligent design by an omnipotent deity should necessarily be restricted to Earth]. Oh, look! Paul's smoking dope! How funny! Or not, to be honest. Maybe it just seems unlikely that an extra-terrestrial would have so wholeheartedly embraced Earth culture while being imprisoned by it, to the extent that the most "alien" creator is probably the one-eyed RV park concierge they pick up along the way - whose presence serves little purpose beyond proving that Graeme and Clive aren't gay (well, Graeme, anyway). It feels more like the duo pick up Seth Rogen as a hitch-hiker than anything else, which is about what you'd expect from the director of Superbad. It might have been different had Pegg and Frost been paired with usual associate Edgar Wright: he was off doing the vastly over-rated Scott Pilgrim. If this is a litmus test where the humour comes from, no-one comes off too well, though the entertainment value from the comedic chemistry merits a viewing, providing no actual cost is attached.