This is the first fantasy film ever to win a Best Picture Oscar. It also tied records set by Ben-Hur and Titanic in winning all 11 Oscar awards for which it was nominated.
In Tolkien's original text, Pippin died at the Battle of the Black Gates. C.S. Lewis then pleaded with him to let Pippin live, and Tolkien had Gimli save him. It was a rather unpleasant death he gave Pippin, who was crushed underneath a troll. According to some interviews, the scene in the first film where Pippin is thrown off the cave troll is a reference to this.
The Cirith Ungol stair ledge was built as a wet weather set on the squash court in a hotel in Queenstown. In November of 1999, Sean Astin's (Sam) close-ups were shot in the taping of the first RotK shots, and as a side note Andy Serkis (Gollum) had not been cast yet. The set remained standing on the squash court and as things would go, it wasn't until a year later on November 30th, 2000, that Elijah Wood's (Frodo) first close-ups were actually shot on that ledge.
Originally, Frodo was to push Gollum into the lava in Mt. Doom, but director Peter Jackson was against it because it made Frodo into a murderer and was out of character.
Another "Wilhelm" scream can be heard when Legolas is climbing the Oliphaunt and throws one of the Haradrim off.
According to the commentary, Peter Jackson said that he shortened the scene of Smeagol strangling Deagol for the theaterical version because if he had not, it would not have given the film its PG-13 rating. The full strangling scene appeared in the Extended Edition.
The great grandson of Lord of the Rings author JRR Tolkien has landed a spot in the final movie, Return of the King. 34-year-old Royd Tolkien was asked by director Peter Jackson to play a Gondorian Ranger in the final movie.
A bit of trivia for those who haven't read the books. In the Grey Havens scene, the three Elven Rings can be seen upon the hands of their bearers: Vilya, mightiest of the Three, is worn by Elrond; Nenya, the Ring of Adamant, is still borne by Galadriel; and Narya the Great is seen on Gandalf's hand.
The scenes at the Black Gate were shot at the army munitions training ground because of its wide, flat, desert type landscape. Before the shoot, the land had forty years worth of demolitions, land mines, mortars, grenades, etc., lying all over. The government asked the army to clear and dispose the ammunition for the filmmakers, but due to the soft ground many could've remained undetected. When the crew arrived for the shoot, an army officer lectured them and showed them different types of munitions to warn them of the possibility of finding more on the site, as dirt was kicked up during battle sequences. There were bomb disposal people surrounding them and sure enough shooting halted as things were discovered and cleared. The cast and crew were told that if they strayed from the designated areas and lost limbs, the army was not responsible.
In the Extended Edition the Gondorian soldier who was shot by an Orc in Osgliath was a cameo appearance by film's stunt cordinator, according to director Peter Jackson on the director/writer audio commentary.
The famous "Wilhelm" scream makes a reappearance during the scene where Faramir's men are fleeing from Osgiliath across the Pelennor Fields. Just after the people of Minas Tirith call out, "The White Rider" a Nazgul swoops down and snatches up one of Faramir's men. The "Wilhelm" is heard as he falls.