Due Date
Zach Galifianakis, left, and Robert Downey Jr. are shown in a scene from "Due Date." Warner Bros.

Remember the John Candy/Steve Martin comedy "Planes, Trains and Automobiles"?

If so, "Due Date" will bring it back to mind because it's a blend of that film and "The Hangover." Even though it isn't the most original comedy ever made, it does have some funny moments. And the two leads have a nice chemistry (mostly of loathing for each other) that's entertaining.

It's no surprise that director Todd Phillips, who also helmed "The Hangover," includes some of the same kinds of situations here. This one isn't as clever, or as funny as that hit, but some of the laughs are almost as enjoyable.

Once again, this is the story of an unanticipated road trip. Peter (Robert Downey Jr.) is trying to get home for the birth of his first child. He runs into Ethan (Zach Galifianakis), who brings destruction in his wake at every turn. Peter, an architect who leads a professional, polished life, can't stand to be around people like Ethan, who can't seem to think past beyond the next minute or two when it comes to planning.

The two end up simultaneously at an airport where both are placed on the no-flight list after Ethan creates a bizarre situation that gets them involved with a TSA agent when he insists on talking about bombs and terrorists. When Ethan offers him a ride, Peter is leery about the situation but accepts out of sheer desperation.

As the miles go by, Peter realizes that not only is he traveling with the type of person for whom he has contempt, but he's also riding with a man who should never get behind the wheel. Ethan has glaucoma, so this means he has to take a side trip to buy weed from a "pharmacist" (a hilarious Juliette Lewis). And the only time Ethan seems to have trouble falling asleep is when he's not driving.

Additionally, you know something weird is going to happen when Ethan tells Peter he has stowed the ashes of his beloved father in the coffee can he's carrying.

There's a lot about "Due Date" that's hard to buy, from Peter's acceptance of the ride from Ethan (he doesn't have a single friend or relative who would come to get him?) to a couple changes of heart that don't seem to fit either character but serve only to move the story along.

Still, its leads are entertaining and most of the jokes work. You could do worse than hit the road to see "Due Date."