It seems like you might not be properly escaping user input for their name by the looks of the leader board which is now popping up a window with a dude getting slapped in the face with a projectile.
Also the matching words shouldn't be passed to the client, keep as much data server side as possible to elevate some of the cheating, your never going to stop all of it but that should deter most people.
All in all though kudos, looks a decent outcome for a hack project.
Edit: You might want to change the page's title. Also, thanks for the game. I really enjoyed it.
edit: aaaand someone crashed the server :/