One thing we know for sure, should aliens ever come to live among us – they will be wise-cracking comedians. The spirit of the Catskills clearly transcends time and space to inform interstellar visitors from Mork to Alf to Gilbert to Roger.

Keep up! That’s Gilbert from 80s kids show Get Fresh! and Roger from American Dad – if references such as this go over your head, you will certainly miss some of the fun in Simon Pegg and Nick Frost’s latest in-joke infested geekfest, Paul.

This is probably the film obsessive duo were destined to make; incorporating every alien and road trip movie meme going. The pair are said to have watched more than 50 such films before writing this screenplay, and taking a little from each means the end product is inevitably derivative, though entertaining nonetheless.

They play bromantically involved sci-fi nerds Graeme Willy and Clive Gollings – possibly not a huge stretch for their thespian talents – who make the pilgrimage from England to San Diego’s Comic-Con convention before hiring a camper van to tour some of the iconic alien sights of the American West: Area 51, Roswell etc. En route they witness a car crash… and who should be driving but alien Paul, on the run from the Men In Black.

This extra-terrestrial, a triumph of CGI, is voiced by Seth Rogan, while the movie is directed by Greg Mottola, most famed for Superbad. This combination gives the film the feel of a conventional American buddie comedy, more functional without the flair of usual collaborator Edgar Wright that made Shaun Of The Dead, Hot Fuzz and Spaced so distinctive.

It’s a strange mix: set pieces such as disguising the alien in outlandish fancy dress is as mainstream as you can get (not to mention featuring in most episodes of American Dad), while the pro-evolution message is unlikely to endear the film to some in the Bible Belt.

Paul is more restrained than some of his wackier alien forebears; a seen-it-all hippy who encourages the uptight Brits to relax more. Meanwhile, during their flight across the deserts to a very familiar rendezvous point for Paul’s mothership, the trio encounter the requisite angry rednecks and fervent God-botherers. Stealing almost every scene she’s in is Kristen Wiig, a repressed Christian who they free from her overbearing father and introduce to the delights of a less stringent lifestyle. Her cack-handed attempts at swearing are particularly delightful, producing compound farty-balls expletives never heard before.

Mostly the road trip unfolds with just enough amiability and peril. Arrested Development’s Jason Bateman, in pursuit as FBI agent Zoil, is well-judged as the inscrutable counterbalance to the heroes’ laissez-fair attitude, and there are a couple of perfect cameos, which we won’t spoil by revealing here. The two incompetent FBI foot soldiers are, however, clunky comic foils, owing more to exaggerated Three Stooges slapstick than Pegg’s usual dry, knowing wit. There’s that odd clash of comic sensibilities again.

But despite such black holes the adventure is undemandingly enjoyable, even without picking up every sci-fi reference that will be manna for fanboys. The script for the most part cracks ahead briskly, there’s a good showing of decent jokes carried lightly, and Pegg and Frost are as amiable companions as ever. Paul might not be out of this world, but it’s a fun ride.

Review by: Steve Bennett