Ending
I'm a little bit confused about some of the final details.
I understand that once Duster found the birdcage in the sand, he realized Trina had given up her last little shred of humanity in favor of tracking down those diamonds. (And I appreciate we got to see him stuff the bird in his shirt instead of seeing a tiny feathered corpse, which is what I was expecting. So now Duster has a small living creature to be responsible for, the way Trina had.)
But what was going on with Trina and Whatshisname? She somehow walked right up to him in broad daylight, concealing that giant chain somewhere in her little sundress, and surreptitiously padlocked it around his waist and her waist before he noticed? Smooth move.
Did he shoot himself? Surely she didn't shoot a man she was shackled to, in the middle of the desert, WHEN SHE DIDN'T HAVE THE KEY. What happened to the damned diamonds? Were they lying right there and Trina got to bake to death holding her treasure? Did Whatshisname scatter them out and they blended in with the shiny salt crystals so Trina couldn't see them (while she died, still wondering)?
I liked the large theme very much--i.e. "a life is made up of more than one big dream" and the multiple sub-themes regarding connections, responsibility and sacrifices--but the whole movie was plagued with sketchy details.