After the battle with the watcher of the lake outside the entrance of Moria the cave entrance closed in behind them. But somehow Gollum managed to follow them in? I wish that had been more consistent.
Maybe you got a point there...Nice question huh...I definitely don't knoe the answer but the thing that I can say is maybe Gollum find some other way but not specified in the movie...Sorry that's all I can say...
