This one is a bit odd. If you join a game and have high ping (varies but over 100) then the animation and hit calculations for the moving blocks glitch out, they do not move smoothly and jump about. Other animations, such as the waterwheel in hole 1, bridges in bridge to nowhere, lift and minecart on hole 18 are all OK.
The swinging axes also glitch, but not quite as badly.
Prior to V0.9.0.4 this was not a problem, and I have played with a ping up to 180 (though badly).
Any chance of adding the ping value in the server selection screen? Its currently not being shown.