The Orc battle cries for the Helm's Deep battle were provided by a stadium of 25,000 cricket fans. Lead by Peter Jackson, they screamed the war chants, which were spelled out on the TV screen.
When arriving on the set to film the scene in which Andy Serkis (Gollum) has to catch a fish, the crew for Lord of the Rings discovered that it had snowed overnight. Peter Jackson had the snow cleared off the set (which included defrosting the river as well as the land surrounding it) by 1:00 PM.
In the wide shots of Legolas, Aragorn and Gimli running after the Orcs, all three performers were running injured. Orlando Bloom had a couple of broken ribs from falling off a horse; Aragorn had a broken toe from kicking the helmet in the Orc funeral pyre scene; and Brett Beattie (Gimli's scale double) had a knee injury.
Billy Boyd and Dominic Monaghan spent so much time up the tree (TreeBeard) during the making of the film that they wrote a screenplay between takes. It was so hard to get up and down to their perches that they were left there during breaks while the rest of the crew went off to eat, though someone was kind enough to pass their food up to them.
It is claimed that Orlando Bloom blinks fewer than five times (although how many fewer times is not discussed) during the entire film, and never when the camera is directly on him.