I have a fun clipless story from my weekend cyclocross adventure-

I watched a CX race on Saturday and decided it looked like fun, so I bought some MTB shoes, put some clipless spd pedals on my mountain bike (it previously wore toe clips), and spent about and hour learning how to dismount & remount. It was difficult- since the pedals were brand new (and I was used to speedplay road pedals), they were very difficult to clip in & out of.
The next day, while warming up, I was approaching a barrier at speeds much greater than what I'd practiced the day before, and, as I tried to dismount, my left foot didn't unclip, and I went somersaulting into the mud in front of the barrier! Somewhere during my gymnastics, my left foot did unclip, however, I'm not sure at which point during the rotation it did so.
I made it a point to exaggerate the unclipping motion during all other dismounts, and didn't have any more problems