The movie follows U.S. Army sergeant Joe Gunn and his tank in the Sahara desert as they attempting to cross the desert to seek for a fabled water-well. When they run into thirsty German troops, they miraculously and successfully manage to hold them off until help arrives.
For an adventure movie based on chase scenes in exotic locations "Sahara" never takes hold because director Breck Eisner and his team of screenwriters can't agree on what the story's about or what tone should resonate against it.
Sahara is many things, but it is not a movie. It is the skull-splitting cacophony of 21 producers and four screenwriters (that we know about, anyway) standing in the same room shouting into their cell phones.
For "Sahara," the problem is that we have the Indiana Jones movies to compare it to, and I'm afraid there's no comparison. It's never more than a likable poseur.