The filming of the Helm's Deep sequences was so grueling and went on for so many months, that Jackson gave all the extras a free T-shirt to commemorate the experience. There were so many extras that they would often recognize each other other extras in New Zealand's main cities, by wearing the shirts. On the front of the shirt was the statement "I Survived Helm's Deep", with the letter M is struck out, indicating "hell" of the experience. Two versions existed. One was in black, with red printing on the back that read "Lord of the Rings
Uruk-Hai Battalion", The other was in blue with silver printing on the back that read "The Lord of the Rings "Elf Regiment".
The battle at Helm's Deep was edited down from twenty hours of footage, shot over a four month period with the rain machine battering down on the cast.
They couldn't recruit enough men in the six foot height area to play Uruk-hai, so men from five foot high were cast as well. They were affectionately nicknamed the Uruk-Low.
Viggo Mortensen was so impressed with the horse his character rode that he purchased him from the owners. The horse was shipped back to New Zealand for the additional shots that were filmed in 2002.
Viggo Mortensen broke two toes while kicking the steel helmet by the orc pyre, and that take is the one that appears in the final cut. Director Sir Peter Jackson said that he was really impressed with the shout of pain Aragorn cried out for the fate of the two Hobbits, realizing only later that it was real pain for his toes. He was also impressed by the fact that Mortensen continued acting, even while so seriously injured. Mortensen later remarked that the only reason it was even mentioned, on the DVD release, was because he was an actor, and that the stunt crew were injured far worse and pushed through it.
Alan Lee: The concept designer can be seen as the Rohan collecting weapons at Helm's Deep (to the left when Aragorn yells "Then I shall die as one of them!").
Barrie M. Osborne: The executive producer appears as a Rohirrim soldier throwing a rock down on the Uruk-Hai attacking the gate at Helm's Deep.
Dan Hennah: The art director is getting suited up in the armory at Helm's Deep. Look over Aragorn's right shoulder after Legolas says "They're frightened, I can see it in their eyes."
Peter Jackson: [children] Jackson's children Billy Jackson and Katherine Jackson appear as "cute Rohan refugee children."