On streets where the map grows vertically, my Glitch often starts walking in one direction on its own. Either right or left. And once it starts in that direction, the keyboard has no effect. You can counter the effect, but once you let go of the keys, my avatar moves automatically again in the original direction.
This is happening in Chrome, at least, v 13.0.782.112 on Mac Lion. Was happening on Snow Leopard as well.