The graphics are really cute! My only criticism of them is that it is very hard to distinguish the background from the foreground.
I tried on several browsers, but still ran into the strange tractor beam bug. This is mostly speculation on my part, but it seems as if the tractor beam strength is tied to framerate, as if there was a discrepancy between a Time-based feature (as in, something that uses TimeDelta, like timers) and a Frame-based feature. For example, if the tractor beam was Frame-based, but physics gravity was Time-based, the gravity would apply faster than the tractor beam at lower framerates. Do you think this could be the case?
Great work!