Plot hole: There is no way Dirk, Al, and Eva could have made it from the top of the fort to their camels, raced cross the desert and then hid themselves in the sand all before the train were to have met them. The train was barely visible when Dirk saw it through the scope which means it was much farther away to begin with.
Plot hole: Dirk thinks that Kazim's chopper must only have 20-30 minutes of fuel left because he didn't see any extra fuel tanks on it. First of all there's no way Dirk could know that just by looking, since he doesn't know how long Kazim was flying. Secondly Kazim had been flying around for several hours looking for the gang, so either he would have had to go refuel at some point or he did have extra fuel tanks.
Answer: "Here We Go!" by Clint Mansell. It is on the Sahara soundtrack.