We've seen the alien in Simon Pegg's new roadtrip movieS

Footage at Comic Con revealed at last what the CG alien will look like in Simon Pegg and Nick Frost's Paul - and it was a very familiar shape. Pegg and Frost explained to us why Paul looks so classic.

Oh, and there are spoilers below.

We saw a sizzle reel, and it was hilarious. The road trip starts at San Diego Comic-Con (a fact which elicited extreme yelps of delight from the audience when the footage started), where Pegg and Frost are buying comic books and playing video games and mingling with orcs. There's a great moment when Jeffrey Tambor, playing a weird comic book writer, looks at some of Frost's art and says, "Wow this is great - three tits!" (The woman he's drawn is, of course, a three-titted alien.)

When the duo decide to road trip over to Area 51, that's when things get nuts. "THIS SHIT IS REAL," scrolls across the screen. Then a rogue alien (voiced by Seth Rogen) who has escaped the clutches of some bumbling secret agents and their boss (played with foul-mouthed humor by Sigorney Weaver). The alien, who looks sort of like a cutsey, googly-eyed version of the classic gray, begs the two geeks to hide him in their RV. They're joined by Kirsten Wiig, playing an intelligent design enthusiast who is immediately challenged by Paul the alien, who says, "Explain me, then!" We saw some great quips, like Pegg asking Paul if he's communicating with them through some kind of neural interface, and Rogen says, "Actually I'm speaking English, you fucking idiot." And later, when the gang is menaced by some bikers, Paul pokes his head out of the RV, waves his finger in the air, and says, "Yo, fucknuts, it's probin' time." At which point, the bikers faint.

So who is Paul? He's a "gray" alien for a reason, Pegg, Frost and director Greg Mottola told us in roundtable interviews. He's the classic alien shape that you've seen a million times before, partly because the aliens have been subliminally inserting their images into our popular culture over the years. In case Paul's race ever decides to go public, people won't be so shocked, because they've seen aliens like that for years. "The surprise is, he's not surprising," said Pegg in the roundtables.

The philosophy behind the alien's appearance in the film was to take a super-expensive, high-tech CG creation and put him into a dusty, washed out desert setting, on an RV. Usually, when you see a fancy CG creation in a movie, "the worlds they inhabit were very glossy and colorful," said Frost, so it was cool to put a fancy CG alien into a more dirty, gritty setting where hopefully you'll forget he's created using CG.

Adds Mottola, "Paul is sort of the catalyst character, who doesn't change, but changes everyone around [him.]" Paul, voiced by Seth Rogen, is sort of a grumpy older guy, who's brash and obnoxious in contrast to the main characters' sweetness and repression. Paul is kind of "the cool older guy who shows you the ropes."

Paul is not a pastiche or a satire, said star and co-writer Simon Pegg. Pegg and other castmembers of the "geek roadtrip with an alien" movie insisted that the movie portrays geeks and geek culture affectionately. "Anything we do is done with affection," Pegg told us in roundtable interviews about the film.

Recreating San Diego Comic Con in the middle of New Mexico for some crucial sequences in the film was a huge challenge. Star and co-writer Nick Frost said, "The thing about trying to shoot Comic Con is, if it doesn't look like Comic Con, we're going to get killed." The good thing was, Image Comics and other comics publishers were good with being included in the film - everyone except Marvel Comics, who said no because there are references to casual drug use in the film.

It's such a great recreation of Comic Con, the fans "should be jerking off," said Bill Hader in the press roundtables. "Should be a big geek-gasm."

The movie is every Comic Con's visitor's "dream of a movie," said Sigourney Weaver in the roundtable interviews. "This is their story. It's very funny, very touching. It's got a great love story. Kristen Wiig plays a great character in it. I find the story so witty, and just great."

The other challenge was getting extras who would be in costume. Pegg said he was worried it would be "just me and Nick and 20 Slave Leias" standing around. But it turned out a million fans and Comic Con afficionados live in New Mexico and were happy to show up in costume. And the production designer managed to create an absolute perfect double of the real Comic Con.

Director Greg Mottola (Superbad, Adventureland) said he was attracted to Paul because it sounded like a great road movie that had characters, and real character development - and which just happened to have an alien in it. "It's a very warm, affectionate movie." And as a road movie in the Southwest, it's a tribute to some of Steven Spielberg's earliest movies, including Sugarland Express and Duel.

And Paul is also a bit of a classic action movie, with car chases and action sequences and big set pieces - but Mottola, similar to his previous films, finds lots of quiet, human moments for his characters throughout. "The reason he's such a great director is, he's got a big heart," said Jeffrey Tambor.

As for science fiction legend Sigourney Weaver, she plays a crucial role that Mottola, Pegg and Frost were anxious to keep under wraps. But Weaver did spill a few details. "There has to be a heavy in every movie," Weaver told us in the roundtables, and that's her. "She's probably misunderstood." She added: "I have a history, in my career, of being at odds with the alien and this tradition continues in this movie."

Tambor told us he plays Adam Shadowcraft, a science fiction writer - the main chracters, played by Pegg and Frost, are huge fans of his books, until they wind up coming into conflict with him. And this launches them on their journey.

Tambor described his character as a pompous ass. "Remember that guy you went to shcool with, the guy who knew everything? He's a guy who 's hit [big], he's done book after book after book, to great success... He is too full of himself, and he hurts these guys." And then later they turn the tables on him and deflate his ego a bit. (Tambor helped copy-edit our notes during the roundtables, and we promised to credit him.)