Robert Downey Jr. may be one of today’s most watchable actors, but it’s not much fun watching him be the victim of Zach Galifianakis’ shenanigans in Due Date, their disappointing road-trip comedy. Playing two strangers -- with very different personalities, of course -- who learn to accept each other despite some outlandish mishaps, Downey and Galifianakis try to make the most of a film devoted more to a series of silly situations rather than to believable interactions and plot.

To be fair, while sitting through Due Date, I couldn’t help comparing it to The Other Guys, a much superior recent comedy which also follows two characters with extremely opposite personality characteristics. The Other Guys emphasizes clever and humorous  dialogue, while Due Date accents ridiculous incidents and visual gags. I realize it’s a matter of the viewer’s personal taste here, but to me The Other Guys wins hands down.

The plot of Due Date concerns how businesslike architect Peter Highman (Downey) and  eccentric Hollywood-bound Ethan Tremblay (Galifianakis) -- along with his little bulldog Sonny -- manage to drive together across country in time for the birth of Peter’s baby. They wreck a car, get waylaid at the Mexican border, fight with a man in a wheelchair, enjoy a marijuana high, face a near catastrophe involving the ashes of Ethan’s father -- all mostly because of Ethan’s strange behavior. Peter also sustains a variety of bodily injuries during this perilous journey. So the big question is: will Peter realize that Ethan has a big heart and forgive him?              

I don’t think Due Date is a completely bad film. Downey (Iron Man 2) gives another impressive performance, and the movie includes some amusing moments, especially when Downey’s character asks his wannabe-actor traveling companion to act out various scenes for him. The changing expressions on Downey’s face and the simplicity of Galifianakis’ (The Hangover) interpretations are priceless. Both actors shine in those instances.

Appearing briefly and adding a welcome relief to the road-trip misadventures are: Jamie Foxx (The Soloist) as Peter’s friend, who might have been overly friendly with his wife; Michelle Monaghan (Trucker) as the worried mother-to-be; and Juliette Lewis (Aurora Borealis) as an eager-to-please drug supplier.   

WARNING: Due Date contains a crude masturbation scene which contributes nothing to the film except a feeling of bad taste for many viewers. Gasps, not laughs, were heard at the screening I attended. 

ALTERNATE VIEWING RECOMMENDATIONS: Planes, Trains and Automobiles is  available now on DVD, and The Other Guys will be released December 14, 2010, on DVD.

(Released by Warner Bros. Pictures and rated “R” for language, drug use and sexual content.)

For more information about Due Date, go to the Internet Movie Data Base or Rotten Tomatoes website.