Rhcp, let me first explain, the following critiques are in no way, shape, or form meant to insult you. Rather, I've always felt, both in critiquing and receiving critiques, that no good comes of it unless one is honest with the author. There was a lot of interesting aspects of this script, and yet there is much more work to be done. Here is what I feel may deserve reconsideration:
First of all, I would be careful with the subject matter. Being stranded on an island is a commonly visited plot line (which is not an issue here, just a fact). Unfortunately, that means for you, that no matter what you do, your work here will be inevitably compared to LOST, a hit television show that, while not competing against you in this particular medium, has an extremely strong following in this current season.
Let me say, the romantic aspects, you've pretty much made apparent. Four youngs kids, two boys and two girls. Pretty obvious. The trouble is, you make their dialogue, and their relationships, completely unbelievable.
JACK: "You don't have a boyfriend, do you?"
JACK: "That surprises me, as beautiful as you are."
Let me just say, men, no matter how bold, usually don't just act straight-forward like that; and even when they do, the girl usually doesn't seem to fall for it. There are the scenes when Matt and Jack explain to their "love interests" how they've never met another girl like them, and that, even though it's only been three days, they feel like they're in love. Et cetera, et cetera. It simply falls on its face with its abruptness and straight-forward qualities. Heck, with the above dialogue sample, Jack's first line would work better, if, for instance, Emma chuckled and replied, "Well you don't waste time, do you?" At least then, the character realizes how abrupt it is, rather than just accepting it and kissing him.
In fact, the dialogue in general may need some work. For instance:
CHARLES: I'm not feeling too well.
JACK: You haven't been feeling well have you Charles?
CHARLES: Is it that obvious?
Yes, it is that obvious, because you just said it. I get the direction that you are trying to go, Rhcp, but try to make it simply a tad bit more eloquent and not so abrupt. Sometimes dialogue that isn't 100% plot driven isn't always a bad thing. Quentin Taratino, anyone?
The leaves-into-bowls idea is interesting, but altogether a tad bit odd. I find it to be much more realistic if coconuts grew on the island, and the survivors instead used the shell of those as bowls.
I like Charles' withdrawal feature; it makes his character a tad bit more believable. However, you again are treading on the line of LOST, especially see as how the character who goes through detox on that show... is named Charlie.
Watch out for that. Also, it'd be better if the grown man put some effort forth in catching food, making bowls, etc. He seems pretty useless most of the time.
Be careful of having the entire cast become absolutely bipolar at moments. Charles is extremely sick, but upon drinking the water, is so refreshed that he never feels another pain again (well, until he collapses). At that point, Matt, who has been pretty optimistic up 'til that point, replies to this good news with "Well that's great, but we're still stuck on this damn island!" Way to kill the buzz, bro. Even the girls are odd sometimes; while the boys are walking the island, Emma and Ashley chat about them like giddy little schoolgirls.. yet upon their return, Ashley immediately asks "You didn't find a fresh water supply, did you?" as if all giddiness has instantly vanished and be replaced by a survival guide-esque mastery. Two days after meeting Matt, Ashley is already ready to leave her fiance for him. Not only that, but why does, by the middle of the script, the fiance become the husband. They are correlations and logistics that lack here.
In terms of format, you may want to switch the "NEXT" time tag for the more professionally-accepted "CONTINUOUS;" personally, I don't mind bending the rules on structure from time to time... still, sometimes, I find it the best way to function with certain projects.
Also, if you are intent on using Word, rather than a screenwriting application, you may want to consider using the Tab button rather than the Center Alignment feature; again, the look is far more aesthetically pleasing, and more industrially accepted. Staying orthodox isn't always a bad thing.
"DISSOLVE TRANSITION" could be easily replaced with "DISSOLVE TO," seeing as how you are already using "CUT TO" anyway.
And the ending... the sunset scene seems miles from what the rest of the story entails. Right upon arriving, Ashley confesses her love to Matt, Matt hits Shane, and Shane accepts it, without any military officers even stepping in to break up the fight. Then Ashley and Matt leave in a convertible, into the sunset. This is no longer a story of survival; the last scene practically sums it up as a stranded-on-the-beach romance. And with all due respect, this is a concept that deserves more than that.
Again, I ask you, please don't take offense to some of the comments, no matter how they came across. I'm really interested in seeing more of your work. But there are certain plot points that, if not worked out properly, could stab you in the back.