It got stuck in the snow. I saw almost the same thing happen at Anfield in 1981 only difference was the ball stuck in Mud just before crossing the line after Ian Rush had rounded the keeper and "scored" only for it to stick about a foot short I was in the Kop at the time with some mates including a couple of their lasses who thought it was funny - few scary moments as the Liverpool fans around us didnt take too kindly to anyone finding that funny. It was made even funnier by the fact that Liverpool were losing 1-0 at the time and time was running out
With Hannover currently in a relegation battle that could be very important at the end of the season...