By the time The Fellowship of the Ring, the first of Peter Jackson's Lord of the Rings movies, hit theaters in December 2001, the next movie was already in post-production. All three adaptations of JRR Tolkien's classic fantasy series were shot simultaneously, with principal photography ending in late 2000. So no matter how Fellowship fared at the box office, New Line Cinema, who financed the film, were committed to releasing the next two parts. Luckily, it was an enormous success.

Expectations were extremely high when The Two Towers was released in December 2002 but again, the movie didn't disappoint. While Jackson and writers Fran Walsh and Philippa Boyens didn't have the advantage of presenting a new and exciting world for the first time like they did with Fellowship, they were able to throw audiences back into a gripping story with established heroes, while introducing new characters and expanding the mythology of Middle-earth.

As for the action, The Two Towers was absolutely spectacular. The fight with the vicious Wargs was thrillingly realised, while the siege of Helm's Deep is simply one of the greatest cinematic battle sequences ever filmed. Like all second films in trilogies, there isn't a conclusive "ending" as such, but there were very few viewers who weren't immediately planning to see The Return of the King a year later.

An extended version of The Two Towers was released on DVD in 2003, and like the Fellowship release, it was packed with fascinating commentaries and behind-the-scenes footage. We've been back through this bonus material to find some fascinating behind-the-scenes facts, references, and Easter Eggs. And once you've read this, check out our guide to all the things you missed in The Fellowship of the Ring.

1. The studio wanted a prologue

Although New Line didn't want a prologue at the start of Fellowship of the Ring, Jackson eventually persuaded them. Conversely, executives at the studio wanted Cate Blanchett to return to narrate a new prologue for The Two Towers, to recap what had happened so far in the story. But Jackson felt it wasn't needed and refused.

2. The opening scene had a surprising inspiration

Jackson stated that the distant sound of the voices from the first movie, as the fellowship face the Balrog in the mountain, was influenced by Back to the Future Part 2, where characters revisit events from the original film.

3. The Balrog fight was influenced by a painting

The scene of Gandalf fighting the Balrog as they fall through the mountain was inspired by the paintings of John Howe. The acclaimed illustrator's illustrations of scenes from Tolkien's books led Jackson to hire Howe as one of the movie's main conceptual designers.

4. This scene was added during post-production

The extended cut scene of Frodo and Sam talking about food seasoning was filmed months after the main production had finished, while the movie was being edited. Jackson decided the pair needed a lighter scene near the beginning, before things start getting very serious.

5. A real volcano was used as a location

These scenes of Sam and Frodo were filmed on Mount Ruapehu, a volcano on New Zealand's North island. The volcano subsequently erupted in 2007, and in 2016 increased volcanic activity led geologists to warn tourists and visiting movie fans to stay away from the location.

6. Gollum wasn't added to these shots for two years

These background shots that would later include Gollum were shot two years before the CGI character was placed into them. "You're praying one day you're going to have a great looking creature there," Jackson said.

7. This orc drink sounds quite tasty

The "medicine" that the orcs give to Merry was a mixture of peach tea and cola syrup.

8. This Uruk-hai actor also had an important role in The Fellowship of the Ring

The Uruk-hai who says "man flesh!" is played by actor Sala Baker, who also appeared as the armored Sauron in Fellowship of the Ring.

9. All three actors in this scene were suffering from injuries

Viggo Mortensen, playing Aragorn, had broken a toe (see slide 17), Brett Beattie, playing Gimli in the wide shots, had dislocated a shoulder, and Orlando Bloom, as Legolas, had cracked a rib falling from a horse. "I was shooting the running guys like the walking wounded," Jackson said.

10. This montage reused footage from Fellowship of the Ring

The montage of Saruman's army preparing for war, as they chop trees and stoke "the fires of industry" is comprised of reused shots and outtakes from The Fellowship of the Ring.

11. It took many hours to put make-up on Bernard Hill

Hill had to sit for 4 to 5 hours every morning while his make-up as the old, decrepit Théoden was applied.

12. Brad Dourif shaved his eyebrows five times

Dourif's scenes as Gríma Wormtongue were filmed in five separate blocks over the course of two years. Every time Dourif flew out to New Zealand to shoot more scenes, he had to shave his eyebrows off.

13. The camp sequence was originally two scenes

The overnight camp scene on the outskirts of Fangorn Forest, in which Merry and Pippin escape and the orcs are attacked by the Riders of Rohan, was cut together from two seperate scenes, which were originally set on different nights. But to speed the pace of the movie up, Jackson shot some extra footage and made it all one longer scene.

14. Some orcs have a familiar voice

Gollum actor Andy Serkis voiced two of the orcs in the camp scene, who have consecutive lines: "We ain't had nothing but maggoty bread" and "Why can't we have some meats?"

15. John Rhys-Davies wasn't on set for this scene

Rhys-Davies's double, Brett Beattie, played Gimli for the wider shots in the scene where our heroes encounter the Riders of Rohan. Jackson said that much later, he got Rhys-Davis back into make-up, "stuck some horses behind him," and filmed the close-ups shots of Gimli to insert into the scene.

16. The decapitated orc head didn't make it to TV

For the TV version of The Two Towers, the severed orc head was hidden by a helmet.

17. Viggo's scream was very real

When Mortensen kicks the orc helmet, he's really screaming in pain. Viggo broke his toe and fell down in genuine pain. Filming was halted and the rest of the scene was completed the next day, with Mortensen limping painfully. His foot was bandaged under his costume for several weeks afterwards.

18. Fangorn Forest was entirely fake

Jackson and his team couldn't find a forest in New Zealand spooky and evocative enough to stand in for Fangorn Forest. So the forest was built on a set, and all the trees are amazing replicas.

19. This scene was constantly interrupted by aeroplanes

The Fangorn set was built in a warehouse next to an airport. Jackson said that the shots were interrupted every few minutes by the roar of planes taking off. The dialogue track in the scenes leading up to the appearance of Gandalf the White had to be cleaned up and rerecorded in post-production, and on set the actors simply had to keep going while planes took off around them.

20. Jackson didn't know what to do for this cosmic sequence

Jackson struggled to visualise Gandalf's journey to becoming Gandalf the White after killing the Balrog. In the movie commentary, Jackson says the script simply reads "death birth cosmic weirdness" at that point (you can see it on page 60 here).

21. Treebeard was a mix of prosthetics and CG

Treebeard is a large prosthetic model, on which actors Billy Boyd and Dominic Monaghan were held in place by wires. The wires were painted out digitally and a CGI Treebeard head was added afterwards.

22. Gandalf's fake nose caused problems

Jackson says Ian McKellen was initially "very much against" the idea of wearing a prosthetic nose as Gandalf, because he knew he'd have it applied daily for the next 15 months of shooting. However, McKellen ultimately agreed to the nose. The appliance did cause issues at times however. In this scene, the material the nose was made of didn't reflect light properly and appeared black when Jackson viewed the footage shot that day. The color had to be adjusted digitally, and Walsh says there was a "tense week" while she and Jackson waited to hear if this could be done by WETA, or if the entire scene would have to be reshot.

23. Sean Astin was in great pain in this scene

Viggo Mortensen wasn't the only actor to hurt his foot making The Lord of the Rings. Sean Astin stepped on a broken bottle while filming in a lake at the end of The Fellowship of the Ring, and had to have stitches. This Two Towers scene was filmed soon after against a blue screen in a gymnasium, and Astin was in a lot of pain, which is why he only walks a little way before sitting down.

24. There are two black gates because of a typo

The reason there are two black gates to Mordor, instead of the single gate everyone talks about, was simply down to an error. Walsh accidentally wrote "gates" when she put her request into the modelmaking team at WETA.

25. Jackson says Monty Python made this scene hard to take seriously

Jackson found it difficult to visualise the Rohan villagers, because of a classic Monty Python movie. "It's always hard to do peasants in films," he said. "You always think of Monty Python and the Holy Grail [shouting] "Bring out your dead!"

26. This important scene was added much later

The stable scene in which Gandalf tells Aragorn that he must protect the people of Rohan was shot two years after the preceding scene, while the movie was being edited, in order to give Aragorn a purpose for the rest of the movie and to tease Gandlaf's return much later.

27. The editing makes this scene unnerving

Andy Serkis performed the Gollum/Sméagol conversation in one continuous take, but when editing the film, Jackson decided it was more disturbing to cut between Gollum and Sméagol as if they were two separate individuals.

28. Andy Serkis's audition helped create more than just Gollum's voice

Serkis initially just auditioned to perform Gollum's voice, but his physical movement and facial expressions in the audition were so impressive that Jackson asked WETA to use the audition tape as a basis for animating Gollum.

29. A CGI Orlando Bloom jumps onto his horse

The shot of Legolas jumping onto his horse before the Warg attack is one of the most iconic moments in the movie. However, Orlando Bloom never shot it. He cracked a rib falling from a horse on an earlier day and was unable to get up onto a horse afterwards. Much later, while editing the film, Jackson realized he still needed a shot of Legolas mounting the horse, and with Bloom unable to do reshoots because he was making another movie, the moment was created with CGI.

30. This orc actor appeared in a classic early Peter Jackson movie

The orc who tells Gimli and Legolas that Aragorn has fallen off the cliff is played by Jed Brophy, who previously appeared in Jackson's incredible 1992 splatter comedy Brain Dead (aka Dead/Alive) as Void the punk.

31. Viggo became very attached to his horse

Mortensen spent a lot of time with Uraeus, the horse that plays Aragorn's horse Brego. He even slept in the stables with him, so that the horse recognized and trusted him for the scenes in which Brego helps save Aragorn after he has been swept downriver. Mortensen subsequently bought Uraeus and continued to look after him. He wrote a moving tribute to him when he died in 2015, age 28.

32. This map was inserted later in post-production

The inserts of Faramir pointing at a map were shot long after production, to help the audience understand where the different locations in Middle-earth were in relation to each other. Jackson was in post-production in London when he decided the scene needed the extra shots, so filmed himself pointing at a quickly drawn map and sent the footage to New Zealand. A real map was then made and filmed, with someone else's fingers doing the pointing.

33. Jackson felt bad he cut Sean Bean out

Jackson says he felt "absolutely terrible" that he edited Sean Bean out of the theatrical version of The Two Towers, as the actor had flown all the way to New Zealand from the UK to film the flashback scenes as Boromir. Luckily, Bean's scenes were reinstated for the extended version.

34. Jackson decided to bring the Elves to Helm's Deep

In Tolkien's novel, the Elves don't come to Helm's Deep to help in the battle against Saruman's army. It was Jackson's idea to include them in the battle, to provide a moment where the odds don't seem quite as terrible for our heroes. In the commentary, Boyens jokes that Jackson said "I don't care about the fans!" when she and Walsh said the fans might not like this change.

35. Arwen was originally going to feature in the battle

Liv Tyler filmed some scenes as Arwen, fighting alongside Aragorn and the Elves at Helm’s Deep. Although most of these don’t appear in the movie, she can still be spotted very briefly in some shots.

36. This close-up shot helped an extra

This extra is really missing an eye, and was asked to take his eyepatch off by Jackson. In the commentary, Jackson says he was reluctant at first, but eventually agreed, and later thanked the director for making him feel much less self-conscious about it once he saw his close-up on screen.

37. The Ent scenes are deliberately frustrating

The decision to cut away from the exciting battle at Helm's Deep to scenes of the Ents unable to decide whether to help or not was intended to annoy the audience. "The irritation was deliberate," Jackson said. "There's the desperate fight where our heroes are fighting for their lives, and some miles away there's this group of trees trying to figure out what to do."

38. There was only one serious accident on set

The only serious accident that occurred while shooting the movie was the moment a soldier gets hit by a large catapulted grappling hook during the Helm's Deep battle. The stuntman was pulled back against the wall by a wire, but landed awkwardly and broke his leg "very badly."

39. This shot of Minas Tirith was removed in the theatrical version

Minas Tirith was removed from the background of this shot for the theatrical version, because executives at New Line were worried it might be confused for Helm's Deep, and that Faramir and Frodo were heading there to join the battle. Jackson reinstated it for the extended cut.

40. Jackson thought the burning Ent might upset children

One of the Ents is set on fire while fighting Saraman's orcs, but Jackson decided it might be too upsetting for kids, so asked for a shot of the flames being extinguished when the water floods Isengard.

41. Sam's monologue was never filmed

Sam's speech to Frodo about storytelling and never giving up was never fully shot. Much of the dialogue was written later by Walsh and Boyens to make the scene more emotional. Sean Aston recorded the dialogue, which was then overlaid on a montage of the other characters.

42. Frodo and Sam's final scene was added during reshoots

Jackson wanted to give the characters a friendly, lighter moment after the drama of the previous scenes, where their relationship is pushed to the edge.

43. This lengthy shot of Gollum was very complicated to film

This final scene of Gollum plotting against Frodo and Sam is the longest digital shot in the movie. It was essentially filmed three times--once on a steadicam, with Andy Serkis acting as Gollum, a second time with the steadicam operator replicating the same movements but without anyone in the frame, and a third time on a soundstage with Serkis doing the same performance in a motion capture suit for WETA to create the CGI Gollum. Jackson described the shot as "nightmarish" but wanted to include it without edits to help convey Gollum as a real character and not just a digital creation.