After seeing your tweet of the gameplay, I see what the issue was. The arrow and wave it rides on, don't render in chrome for me. So there is nothing for me to sync the ? block to.
Ah jeez, that's an unfortunate bug! Sorry about that but cheers for the heads up. I haven't been able to reproduce it in Chrome but there are definitely some quirks I've seen machine to machine with this web version that I'll be looking into. If you'd like to give this a proper try and have something running Windows, the downloadable EXE should perform much more sensibly :)