You could make a case that any movie in which Mexicans and rednecks become best of friends is a net positive for society. But to do that here, you'd have to ignore the severe boredom that sets in about halfway through this comedy -- a Three Amigos with fewer laughs -- in which Larry the Cable Guy, Bill Engvall, and DJ Qualls play useless weekend warriors who somehow never imagine that being reservists in wartime might result in actually having to go to war. Sure enough, they get called up, but one preposterous accident later, wind up in . . . Mexico . . . which they think is Iraq. Tee hee. By the time they figure out where they are, the guys have run afoul of an evil bandito named -- wait for it -- Carlos Santana (Danny Trejo, doing his damnedest). Surely nobody expected Delta Farce to be much better than Ernest in the Army or Pauly Shore's In the Army Now; what's sad is that it doesn't even live up to the comedic "standards" set by last year's Larry the Cable Guy: Health Inspector.