Is it possible to drop a foot in corners while using clipless pedals?
As your pedals age and cleats wear it will get much easier to unclip at a moments notice.

Until then, you can try adjusting the tension of your pedals or do as I did and just ride at slower speeds until more comfortable with cornering while being locked in.  

Even with looser clips and experiance I still fall, but that wasn't any different then when I was using flats :)