Do you mean you can't tink back stitch by stitch or that you can't use a crochet hook to go back down a few rows to fix a stitch?
One thing you can do is to use a lifeline when working a complicated pattern (or any really). Put a length of smaller gauge yarn or embroidery floss on a yarn needle and run it through the stitches on the needle after you've done a certain amount of rows and then move it up as you get more done. I think it's usually best to do it after each pattern repeat so if you have to rip back you now right where you are. There are 8 rows to the pattern repeat on this scarf you linked to so at the end of row 8 you put the lifeline in.