Judging by the quick turnaround of the film, however, there is the sense this may be a mere stopgap film for its participants. The hangover after The Hangover that precedes The Hangover 2, as it were, and something nice and easy for Robert Downey Jr to do before he ends up cracking wise in front of a blue screen, or dressing in period costume, for the next decade in The Avengers/Iron Man/Sherlock Holmes movies. Peter Highman (Robert Downey Jr) is a highly-strung, neurotic businessman who has to get home from a business meeting in Atlanta in time for the birth of his first child at home in Los Angeles. After a chance meeting with aspiring actor and oddball, Ethan Tremblay (Zach Galifianakis), a series of unfortunate incidents brings the two men together and forces them to travel across the country together. One of the primary reasons for the success of The Hangover was that it managed to impose an original and interesting structure onto the tired format of the outrageous buddy comedy. By contrast, Due Date is one of the more formulaic and derivative films I’ve seen for a long while. It’s like a comedy Frankenstein’s monster, stitched together by scenes from other, better films, like Midnight Run, The Big Lebowski, Dumb And Dumber, The Odd Couple, Phillips’s own Hangover and Road Trip, and of course Planes, Trains And Automobiles. For a good road movie to work, however, either there has to be a strong thread of character development to tie the scenes together into something meaningful, like in Midnight Run, or Planes, Trains And Automobiles, or the scrapes have to be so rambunctiously funny that you are carried along regardless, like in Dumb And Dumber (although, granted, your mileage may vary). Due Date fails on both of these counts. While there are funny moments in the film, we’ve seen the majority of them a hundred times before. Moments like Downey Jr getting mistaken for a terrorist on an airplane, or when he ends up getting accidentally stoned, or when the ashes of a dead relative are horribly mistreated. We go into every one of these scenarios with a rough knowledge of how they are going to play out, and our expectations are rarely subverted. As a result, it’s hard to get that enthusiastic about them. There is no sense of consequence or escalation. Horrific events occur and then there is barely a reference to them in the following scene. Character development is almost completely non-existent. Ironically, this means that there is never any sense that we’ve been on a journey with these characters, and as a result, it’s hard to feel too invested at any point. It doesn’t help that Due Date has no real ending to speak of, fizzling out weakly in its final scenes. The filmmakers might argue that traditional character arcs of the ‘I really learned something today’ variety are for safe, twee sitcoms like Two And A Half Men, satirised in the film as brainless fare enjoyed by morons like the Galifianakis character. But you can’t have it both ways, as Phillips tries to here. The moments where Galifianakis and Downey Jr break down and reveal their private neuroses come across as cynical attempts to inject some pathos into a movie that isn’t constructed well enough to support it. The scenes are well played, but compared with John Candy’s breakdown in the train station at the end of Planes, Trains And Automobiles, it’s nowhere near the same league. Due Date is at its best when it is at its most uncompromising and unpleasant, and by far the biggest laughs in the film come on the occasions when the mad-as-hell Downey Jr lashes out and does something completely unexpected and indefensible. It’s just a shame that this spirit only manifests itself a few times in the film. Zach Galifianakis is fine, and has some funny moments as you’d expect, but overall this is the same idiot man-child character we’ve seen from him and a hundred other portly, funny looking comedians over the years. He very much appears to be becoming the new Will Ferrell, transitioning from the fringe of alternative American comedy to mainstream movie vehicles with an adapted version of his own brand of ultra awkward humour. This is not necessarily a bad thing, but he’s still much funnier when he’s allowed to go full-blown weirdo in his non-movie material, such as his work with Tim and Eric, his stand-up, and the ‘Between Two Ferns’ videos on Funny or Die. But what was the point of casting Michelle Monaghan as Ethan’s pregnant wife, in the process re-uniting her with Kiss Kiss Bang Bang co-star Downey Jr, if they only share one 30-second scene together? Obviously, the nature of the storyline prevents them being together for the bulk of the film, but it’s still disappointing that their natural chemistry wasn’t capitalised on more by the filmmakers. And as for Jamie Foxx, his steady decline into inconsequence since his Oscar-winning breakthrough in Ray continues apace, with a nothing role whose main purpose appears to be to set up a sight gag at the end of the film that falls flat anyway. These laughs are almost entirely down to the keen comic sensibilities of the two leads, however. The script is too weak and uneven to produce anything truly memorable, and as a result, Due Date ultimately has to be classed as a disappointment. Follow Paul Martinovic on twitter: @paulmartinovic.