A guy I know pretty well had one deflect on a quartering away shot on an antelope. The expandable hit near the last rib and somehow turned - wound up travelling along the hide outside the rib cage and went into the shoulder. After quite a wait, he was able to recover the animal about 3/4 of a mile away. Luckily, hit a major artery in the shoulder.

I had one hit a weed (tooth pick sized) change directions right before itstruck a turkey at 36 yards. Arrow still hit him in the back, but he got away. Later, watching the video in slow motion showed one of the blades grabbing the weed stem and the shaft turning just before impact.