I wasn't able to reproduce the bug when I tried the Windows version. I'm not sure if I just didn't play it enough, or if it really is just a problem with WebGL. It happened right away on the web though, so it sure seems like a WebGL thing. For what it's worth. I was using Chrome (Version 71.0.3578.98 (Official Build) (64-bit)) on Windows when I encountered that bug.
Also, on a more subjective level (in terms of gameplay) I felt the length you could pull back from the ball felt either too short, or not sensitive enough. This was true on both versions. It was nearly impossible to get up some really steep hills. I understand it might kind of be the point, but I was kind of wishing it was more sensitive and I could accidentally overshoot more often, rather than struggling so much to get it up the steep hills. Might be worth considering balancing that better.