I think that the reason for the elfs coming to helms deep is to show that men dont stand alone, remember, when Theoden and Aragorn were talking and Theoden said "We are not as lucky with friends as you". Ya and when the Rohiririum was running down to helms deep 1st of all the horses could not Gallop down a hill that steep and 2nd the first row of hoses would be killed by the spears that the Uruk-hi held. 1 other thing that i noticed was that when Aragorn fell off the cliff into the water then he would of sank down to the bottom of the river with all that armor he was wearing and sword. But other than that the books and the movie were great!!!!!!!!!!!!!!!!!!! π