I think I read in one of the trade magazines that Sam, not knowing that Bill was lactose intolerant, had given Bill some milk to drink about 15 minutes prior to the whole Crebain incident. So when they came swooping in Bill was, thankfully, "off-screen." It was a good thing to, because our Fellowship would not have gotten Bill hidden in time and, as they say, the jig would have been up.
-Kevin
No, there are no white riders... only white horses... A minor detail change really, for that scene which already had little resemblance to the book, except that there was a river involved. The white horses were the best part of it!