Other mistake: Just as Gandalf and the Rohirrim are riding into the Uruk-hai and they clash, go slowly, frame by frame. Legolas will be on the right of the screen. Keep going frame by frame. You'll soon see a few pretty clear frames of Arwen with her sword, on her white horse. She's sitting to the right of Legolas. Her long hair is pulled back into a braid. She's wearing pink sleeves. She's the only one on the screen with that color, so you can't miss it (slow motion can be helpful but is unnecessary). The official reason for editing out Arwen (given on the DVD extras) was that during filming Peter Jackson intentionally leaked an image of Arwen at Helm's Deep online to gauge fan reactions, then backpedalled over her presence after overwhelmingly negative fan reactions. (01:30:40)