Deliberate mistake: In the Extended Edition, the location of the Tomb of the Stewards is shown to be behind the city of Minis Tirith, at the cemetery on the mountainside, accessible via a long bridge. Flaming Denethor later runs to the far prow of the city, leaps off and plummets. The distance between the two areas makes it is obviously entirely impossible for someone, even adrenaline charged Denethor, to run this distance while his oiled flesh burns. Admitted on the commentary that it's poetic license, due to director Peter Jackson's long awaited vision for this dramatic shot. (00:13:15 - 00:30:50)
Deliberate mistake: When Théoden and the Rohirrim ride out of camp, as Éomer shouts, "Form up! Move out!" and in the following close-up when Théoden shouts, "Ride! Ride now for Gondor!" please note that Théoden's sheath is at his left side and Éomer's strap hangs down his left shoulder to his right side - whereas normally they are the opposite way. Both shots are flipped for direction continuity. (01:49:30)
Deliberate mistake: Some moments after Gandalf whacks Denethor, the wizard rides Shadowfax up the stairs and all the archers' quivers hang on their right, instead of left. Then, the wizard shouts, "Send the foul beast into the abyss!" in a close-up that is flipped - note Gandalf's cloak broach, which is backwards. Another following close-up of the wizard is also flipped. All done for direction continuity. (02:01:55)
Deliberate mistake: After Aragorn is crowned king he greets Legolas and they place their hands on each other's shoulder. In the shot facing Aragorn when he starts to move toward Arwen, the semi profile seen on Legolas is not Orlando Bloom, but that of his double. In the previous shot facing Legolas, Aragorn and the Elf are the same height and eye level, but in the shot facing Aragorn, Legolas is considerably taller. (02:55:05)
Deliberate mistake: When the combined Rohirrim/Gondorian army halt upon arrival at the Black Gate, Aragorn rides up and stops beside Legolas in the close-up. Éomer's double, who has a much fuller and longer beard, is blatantly visible behind Aragorn in this full frontal shot. (02:28:25)
Deliberate mistake: When Bilbo is boarding the boat at the Grey Havens, in the wide shot, the body doubles are standing at the dock. This is most noticeable on the leftmost of the hobbits, who is standing with his face staring straight ahead, unlike the others who are following Bilbo going up the ladder.
Deliberate mistake: Midst the Rohirrim battle with the Orcs, Théoden shouts, "Make safe this city." Two shots later, in the flipped close-up of Théoden as he hears the Haradrim on Mûmakil, his helmet's chinstrap buckle is on his left (viewer's right), whereas it is normally on his right. (00:31:30)
Deliberate mistake: On the fields of Pelennor, after the great battle, before Pippin and Merry meet again, Pippin's Lorien brooch points to his right. As Pippin is walking and looking around, his brooch is pointing to his left. When Pippin is next to Merry, the leaf is pointing to his right again. Obviously the second shot is flipped. (02:16:30)