How did they get lost so easily? And what happened to Casey's jacket?!?

I wondered about the jacket too!

That was the weakest part. When you start leaving familiar terrain you don't just keep going, that's when you know you've gone too far. Besides they were on the plains, all they had to do was climb the nearest hill to get their bearings, surely, what we saw was like they're left the whole area.

It sounds stupid, but I've gotten lost like that before in a national preserve. I went off the bike trail and eventually blew a hole in my tire. I was essentially lost and had to walk my bike the entire way back. By the time I reached some semblance of familiar territory, it was well past dark and a park ranger found me and drove me back home. This was before the days of cell phones too, which makes all the difference.

So yeah, it is possible to get lost relatively easily, especially when everything looks the same from a distance. But I always assumed they were high or something by the way they were acting the entire time (the whole "rock marooned" sequence). It's also pretty dumb that they didn't bring any water or anything, but I'm not really sure what their initial plan was, anyway.

I guess the fact that it's also based on a true story kind of makes it seem less stupid and more tragic.

It's easy to get lost in natural areas, esp. if you aren't intentionally trying to mark and remember the way back, which they were not. It happens all the time. The moral of the story: Be prepared, when you go out in nature, and let someone know exactly where you're going, what path you'll be taking, and when you'll be back. This was an impromptu stop, so no one knew where they were. They did everything wrong, including not properly marking their path so they could return the same way.