I am also using an Apple Mac Pro with Safari 5.0.4, and am having some issues related to connection. I can usually log in and play, but get lots of "...connection to WGT, blah, blah" errors. Sometimes have to click "RETRY" many times before it continues. Just this morning I was playing in an AS match and watched as my partners counter wound down to :00, then nothing happened. No shot, no warning, just nothing. I assumed there was a problem after a few more seconds and reloaded the window, but instead of being returned to the lobby the message indicated that either me or my partner had forfeit. I found out later that the others were still waiting for me to return to the game.
I went to get coffee and came back to find an error message on the screen (screen capture available if interested) that said "There seems to be a problem with your internet connection. A connection to the WGT servers cannot be established. Do you want to retry?"
A few days ago I couldn't login to WGT at all, and didnt even get an error message. I eventually determined this to be some sort of flash error and rebooted the computer, then logged in normally.
Sometimes the NEWS links on the WGT homepage do not link to the news, but in fact just returns a "http://www.wgt.com/#" location, which means nothing happens. Again, I think this might be a flash issue, but I'm not certain.