The only thing I can think of is to catch the loops and either put them back on the needles and bind off or use a crochet hook and slip stitch them
(then same as bind-of) this sleeve won't look like the other, but if it's not too many stitches, nobody will notice. If you want the sleeves to match, do a decorative crochet edging maybe single crochet because it's simple. If you've run out of yarn completely use some yarn from your stash. It's only a sleeve edge and although not to pattern specifications is I'm sure still beautiful. It will still be made by you and only you will know about the mistake. Go to about.com and look at the diagrams there.

I hope this helps. I know how it is to spend tons of money on yarn only to find you don't have enough or made a mistake. It happens to the best of us.

I'd say that yes, you should be all right. What I'd do is this: take a ~6 inch piece of extra yarn (at the end) which you'll probably have from other tails around your sweater. Anchor one end of the 6" piece on one side of your tail (bind it in as though it was the tail to begin with), then stitch a couple of loops over the wispy tail end, and especially over those first couple of stitches, then bind the other end of the 6" piece in on the far side of the tail. (Does this make sense?) That should anchor down the end well enough to keep it secure.

If that fails, then definitely doing the crochet-binding edge will do the trick.

If none of the other ideas work, you can try just tucking the short end in when you sew the sleeve up and maybe reinforce the end with a couple extra stitches. OR, if you're feeling a little adventurous, you can pull the stitches off from the cast on, put them back on the needles, and knit a new row on and then cast off leaving a long tail. The second one would work if you really wanted to make sure your end stitch didn't come loose with wear.

Either way, good luck!