Darren Bent, Sunderland beach ball goal (VIDEO)

Darren Bent of Sunderland scored an improbable goal in their soccer match again Liverpool when his attempt hit a red beach ball and deflected onto the back of the net. The referees did not wave off the goal, and having been the only goal of the match, cost Liverpool the game in the Premier League.

The scene begs to find out if there are any rules regarding the Darren Bent beach ball goal. If there aren't any, shouldn't there be any rules in place to prevent such improbable circumstances from happening?