British comedy team Simon Pegg (2009's "Star Trek") and Nick Frost (2008's "Penelope") follow up their spoofy takes on zombie movies (2004's "Shaun of the Dead") and action pics/murder-mysteries (2007's "Hot Fuzz") with the alien genre in "Paul," and it's easily the least successful of the three. Taking over for Edgar Wright, director Greg Mottola (2009's "Adventureland") has fashioned an easygoing, benign comedy that plays like a goofier "E.T."-style family film that just so happens to be scattered with four-letter words and sexual innuendo. The references to other films, many of them sci-fi-based and a few decidedly not, are sometimes sly and other times blatant. They're cute enough in a winking sort of way, but the entire film, also written by Pegg and Frost, seems to hinge on these callbacks and never finds its own identity. It's vaguely pleasant and never offensive, but also predominately blah.

Best buds Graeme Willy (Simon Pegg) and Clive Gollings (Nick Frost) are die-hard sci-fi enthusiasts who leave their UK pond for a trip to San Diego's Comic-Con convention. From there, they hit the open road in their RV for a tour of America's most famous UFO hot spots. It is convenient but not exactly coincidental, then, when they witness a car accident in front of them in Area 51, Nevada, and come into contact with an actual extraterrestrial named Paul (voiced by Seth Rogen). A jovial, pot-smoking type with a sarcastic sense of humor, Paul has escaped captivity and quickly joins them, backseat driving as the gobsmacked Graeme and Clive head toward a destination they're left in the dark about. Meanwhile, Agent Zoil (Jason Bateman) is hot on Paul's trail, one step behind him and quickly gaining traction as he reports to his mysterious boss (Sigourney Weaver) back at headquarters.

Give "Paul" this much: it holds the unprecedented distinction of being the only mainstream comedy in existence with punchlines referencing the 2003 child molestation documentary "Capturing the Friedmans" and 1992's disease drama "Lorenzo's Oil." The rest of the film's targets are more in line with expectations, with "Star Wars," "Men in Black," "Aliens," "Back to the Future," "Close Encounters of the Third Kind," and "Mac and Me" all cited at one time or another. "E.T." seems to be its biggest influence, though, with the jokey revelation that Paul instructed Steven Spielberg (in a voice cameo) on the creation of his script for that 1982 blockbuster, a restaurant named Gertie's making an appearance, and an ending that plays like a reenactment. Some of these references are smile-and-nod-worthy, but few are genuinely funny. They also only call attention to how lacking "Paul" would be if they were excised. The premise is fine, but director Greg Mottola doesn't inject the pace with very much inspiration or energy. The picture just goes through the motions.

As Graeme and Clive, the latter a sci-fi writer trying to garner interest in his second book about a female alien with three breasts, Simon Pegg and Nick Frost are as amiable as always, sharing a breezy repartee that gives away what good pals they must be in real life. An ongoing joke about how everyone they cross paths with keeps mistaking them for lovers would, without the right touch, come off as tiresome and homophobic. Here it actually works and is good for at least a few snickers. Breaking up their chemistry is CGI creation Paul. He is voiced well by Seth Rogen (2011's "The Green Hornet"), but is visually unpleasing and never ingratiates himself to the viewer. He may be the title character, but he's also a weak link who keeps Pegg and Frost from letting loose on their own. Better—actually, the best thing about the film—is a very sweet Kristen Wiig (2010's "MacGruber"), getting the heartiest laughs as Ruth Buggs, the God-fearing daughter of devoutly religious RV camp owner Moses (John Carroll Lynch). When Ruth meets Paul, her adamant stance against evolution comes crashing down. Free from the shackles of her beliefs for the first time in her life, she joins the guys on the road and takes a particular interest in cursing and fornicating. Wiig is a delight throughout; it's about time this scene-stealer gets her own movie. Of all the supporting players popping up, most are underutilized, though Jane Lynch (2009's "Julie & Julia") is a memorable bright spot as a friendly waitress at an alien-themed roadside cafe Graeme and Clive stop at.

"Paul" isn't particularly peppy so much as slight and laid-back, and it only loses more steam by the third act as Blythe Danner (2010's "Little Fockers") enters the frame as a woman from Paul's past and Sigourney Weaver (2010's "You Again") finally shows her face for a wasted climactic walk-on. The ending is intended to be simultaneously heartwarming and imprudent, but not a sturdy enough bond has been formed between Paul and his earthling friends for it to have any impact. It doesn't help that Paul just hasn't been terribly amusing. Why should we miss him? All the ingredients seemed to be in place for "Paul" to work better than it does, but more often than not it just kind of sits there. It's good-natured, but not half as sidesplitting or gratifying as it thinks it is.