While Aragorn, Legolas, and Gimli are tracking the Uruk-hai, Aragorn asks "Legolas, what do your elf eyes see?" And Legolas responds, "The Uruks turn northeast, they're taking the hobbits to Isengard!" If the Uruks turned northeast, they would be traveling away from Isengard, since Isengard is northwest of their location.
Just as Ugluk and the troop of Uruk-Hai stop and Uruk asks, "What is it? What do you smell?" one of the Uruk-Hai fails to notice a bump in the terrain and goes sprawling to the floor.
When Eomer gets on his horse after his first meeting with Aragorn, Gimli and Legolas, you can clearly see his sword slipping out of his scabbard and falling down.
In their very first scene when Aragorn, Legolas, and Gimli are seen running on top of a mountain, you can see Gimli's boot/shoe fall off.
When Faramir's party is called back to Osgiliath, they stop on a ridge looking toward the city. In the distance, you can see Minas Tirith, which is west of Osgiliath; therefore the party is on the eastern side of the Anduin. Once they reach the city, one of the men of Gondor mentions that Mordor's forces have taken the eastern half of the city. So how did Faramir's party get to the western side? If they used the sewer that Faramir sends Frodo and Sam into later, why did he have to explain to them what those sewers were at that time? They'd already have been through them once.
When Aragorn is lying on the river's shore, he forces himself onto an unsaddled horse. But, when he sees the Orc Army and starts to gallop towards Helms Deep, he is riding with a saddle.
At Helm's deep, several elves draw and shoot their bows (complete with sound effects) but no arrows are seen.
At the very end of the movie, when Gandalf, Theoden, and rest of the main survivors of Helm's Deep ride over the hill together, and Gandalf says "The battle for Helm's Deep is over. The battle for Middle-Earth is about to begin.", the actor portraying Eomer is clearly not Karl Urban. This shot was done during pickups when Urban was not available, but WETA was supposed to cover up the actor's face with Urban's.
When Aragorn, Legolas, Gimli and Theoden ride out in the Helm's Deep battle, the back row of Rohirrim soldiers are swinging their swords at nothing.
In Helms Deep, when people are moving deeper into the caves (as orcs are storming the keep), we see a woman put her hand on one of the stalactites as she passes it. When she releases it it sways gently.
At times the character Gimli is as tall as Aragorn's shoulders. At other times, he is much shorter. The same error can be seen in The Lord of the Rings: The Fellowship of the Ring when Gandalf and Bilbo embrace.
Legolas' eyes are brown for the majority of the battle of Helm's Deep, instead of their customary blue. However, it is reported that this particular color change came about when Orlando Bloom's blue contact lenses were forgotten during some of the shooting for this sequence.
In the cast list for the Extended Edition, John Noble's name is misspelled, "Nogle".
Aragorn's beard repeatedly changes length between shots in King Theoden's hall.
Normally, Legolas' bow is white, but right before the battle with the Wargs, its brown in the close up.
Several shots after Legolas, Gimli and Aragorn encounter Eomer and his men have been reversed (leaf-brooches are upside down, and Legolas' chest straps and quiver are on the wrong side).
In the extended DVD edition, Dominic Monaghan points out in the cast commentary that in one of the aerial shots of the Uruk-Hai taking the Hobbits to Isengard, Merry and Pippin are nowhere to be seen. This is false. Both Hobbits are wearing green capes which can be easily made out without freeze-framing the scene. The Hobbits are being carried by two Uruks in the third line from the front of the group. (Extended Edition DVD Time Code: Disc 1, 26m20s)
When Gandalf the White first enters Theoden's hall, the position of his staff changes from being held perpendicular to the ground to being held parallel between shots. Director Peter Jackson noticed this error for the first time while recording the Director's Commentary for the Extended Edition of the DVD.
Pippin's hands are tied, but when he falls under the horse, his hands are untied and apart. When Aragorn is working out what happened we see, in the flashbacks, that Pippin did not cut his bonds until after the horse incident.
During the battle of Helm's Deep, Aragorn orders the archers to shoot by yelling 'Fire!'. This command appeared after the introduction of firearms. Earlier, an archer commander would use the command 'Shoot!' or 'Release!'.
In the storeroom where Sam is suggesting that Frodo use the Ring to escape, Frodo is initially sitting in front of a barrel. When Faramir arrives, Frodo and Sam are sitting on a cloak and there are no barrels in sight.
When Theodred is carried to the graveyard, his heavy scale mail armor is caught in the wind; a heavy looking item supposedly made from steel plates with tough leather on the backside, but none the less it flaps in the wind.
When the main characters are standing on the cliff looking out towards Mordor, you can see Helm's Deep over their shoulders. The hole in the wall from the gunpowder is conspicuous by its absence.
As Théoden, Aragorn and the others ride out of Helm's Deep at the end of the battle, when they ride down the "bridge", one of the computer generated Orcs, on the side of the bridge that is closest to the camera, goes straight through one of the horses before he is thrown from the bridge. Also (and conversely), horsemen in the back of the column slash with their swords at invisible targets.
(Flipped shot) When Legolas says in Elvish, "There's something out there," the Elvish Brooches (leaf brooches holding their cloaks together) are facing the opposite direction. Peter Jackson first noticed this error while recording the Extended DVD Director commentary.
When Merry and Pippin are dropped to the ground by the Uruk-Hai, Merry is lying very close to Pippin. In the next shot Pippin is obviously a few feet away for he has to crawl closer to Merry to be able to talk to him
During Arwen's vision of Aragorn's (eventual) death, Aragorn's fingers do not move on his sword as many, many people have suggested - they are Arwen's fingers.
When Theodred is buried, Gandalf's hair is grey and sticking out to the side, in the next shot it is Gandalf's usual color of long flowing white.
When Gamling and Hama ride ahead of the Rohan civilians to scout, and Hama's horse starts to get nervous and Gamling asks what's wrong, Hama is on the right and Gamling is on the left. Then in the next shot they switch places. And when the Warg jumps upon Hama they switch places again.
This was changed on the DVD, but on the original version of the movie, during the battle of Helms Deep the orks launched ropes with hooks on them at the top of the wall. They started to hoist the big ladders with the ropes. Two scenes later they pushed the ladders the rest of the way to the wall but the ropes were not there.
When the Ents are destroying Isengard, there is a shot of Saruman that runs in reverse as he looks down from the top of the tower. One can tell from the motion of his hair and beard.
When Faramir is holding Sam and Frodo in Osgiliath, and is about to let them go, the shot of the Hobbits is reversed (leaf brooches face the wrong way).
Just after Sam says "How could the world go back to the way it was when so much bad had happened?" we cut to a shot of Aragorn which is a reversed shot - the scar on his lip is on the wrong side.
The Orcs use axes to chop the trees into smaller logs, but, when the logs are thrown on the fire, the ends are smooth, as if cut with a saw.
When the Rohirrim are searching for the body of Théodred at the fords of Isen, Éomer rolls over the body of a Rohan soldier. Next to him you can clearly see a piece of yellow and black striped tape (in the bottom left corner), possibly a marker.
When Gimli kills the warg just after the battle on the mountainside, after Aragorn goes over the cliff, there are riders in the background acting out killing moves against the enemy. However there are no enemy present.
While on their way to Helm's Deep, Gimli is telling tales to Eowin and Aragorn in order to while away the long hours of the trip. At several points, however, you can see the direction of the battle ax's head change from blade forward to blade backwards then forwards again, all within mere seconds of each other.
In the battle of Helm's Deep, when the Uruk-hai are about to ram the gate, a camera is seen in the left.
During the battle of Helm's Deep, after the wall has been breached and Haldir dies, Aragorn gets on an Uruk-Hai ladder and drops himself into the advancing Uruk-Hai. In the wide shot it can be clearly seen that the ladder has been raised against the Deeping Wall from inside the castle. When, how and why did the Uruks raise a ladder there, when two flights of stairs are already available?
When Shadowfax first appears, there are tracks across the paddock behind and to the right of him. Some say these are tire tracks, others argue that they could just as easily be the wheel ruts of a farm cart. In response, the first group say that the ruts are too far apart to be from a farm cart, and the space in between is too narrow, meaning that they are definitely those of a car or truck.
The length of the chain in which Frodo carries the ring changes throughout the film
When King Theoden is having his armor strapped on, his aide fastens the left shoulder strap, then we see the leg greaves being strapped on, and gloves being tied. In the next shot, the aide goes to fasten the left shoulder strap again, and there are no greaves on his legs or gloves on his hands.
When Legolas shoots the rope of one of the big ladders, the previous shot has already shown the ladder to be past straight vertical position. The ladder should continue it's arc towards the wall, but instead it falls back.
The position of Legolas' quiver changes from one side to the other and then back again in Fangorn forest.
When Legolas has to hand over his weapons, he takes the knives from his back. When Aragorn hands over his own sword, we see Legolas taking off his knives again in the background.
Shortly after Haldir arrives in Helm's Deep with the Lothlorien army, Legolas stares directly at the camera.
After Aragorn's line "You have some skill with a blade," the sword spin is clearly sped up to appear fast. The people and fire in the background move much too fast, looking like Keystone Cops.
When the gate to Mordor is opened, it is clearly seen to be as thick as the wall, and each corner is seen to be a right angle. There is no space at all in between the gate and the wall when it is closed, later on in the same scene. However, the gate opens on a curve, and so would get stuck every time it opened or closed, unless the wall was somehow retracted. We do not see the wall retracted at all, thus it is physically impossible for such a gate to exist.
Gandalf's horse "Shadowfax" is obviously played by at least two different horses in the movie, as different markings can be seen on the horses.
During the second close-up of Legolas's eyes in Fangorn Forest, you can see that he is wearing contact lenses.
When Gandalf, Aragorn, Legolas, and Gimli are entering Theoden's throne room for the first time, Gandalf turns quickly around when the doors close but in the next shot his head is centered.
When Gimli enters Helm's Deep for the first time, he speaks to Eowyn about Aragorn's fate. Before she speaks, Gimli's helmet is on and his axe is covered in blood. After she speaks, his helmet is off and his axe is clean.
When the Rohirrim surround Aragorn, Legolas and Gimli at the beginning, you can see Éomer's lips moving in one of the wider shots and he obviously talks to the three but there is no sound coming out of his mouth.
When Pippin climbs Treebeard, he has several smudges of blood on his face. These have disappeared seconds later, when Treebeard is holding both Pippin and Merry.
After Legolas shoots two arrows into the shoulder region of the Uruk-Hai running with the torch, the arrows are nowhere to be seen in the shot that shows the runner diving into drain on the side of the wall of Helms Deep.
In the shot where Aragorn orders the men of Rohan to fire their arrows (just after the elves do from the wall at Helms Deep) his sword's blade disappears as it comes toward the camera.
At the end of the film when Gollum is crawling through the woods talking to himself, his hands and feet disappear into the ground.
(flipped shot) When Aragorn is tracking Merry and Pippin from the orc pyre to Fangorn Forest, his ring (usually on his left hand) is on his right forefinger and his glove (usually on his right) is on his left hand.
After the wall is blown up during the Battle of Helm's Deep, Gimli can briefly be seen with a two-headed ax instead of the one-headed ax he should have.
When the men of Rohan are in Helm's Deep preparing for war against the orcs of Isengard, we see Aragorn calls a young boy over to see his sword. After which telling him, "this is a good sword", he brings the sword closer in to his body. But instead of the sword appearing in front of him, it appears behind him.
Unless made of modern synthetics, bow strings will stretch when subjected to water. At the Battle of Helms Deep the bows would have quickly become useless.
When Frodo and Sam are hidden under the elvish cloak at the Black Gate, we can see from under the cape the feet of the enemy soldier through a gap in between the cloth and the floor. But in the next shoot when Frodo unfold the cape (that looks like a rock) we can see it was well buried in the dust and there is no possible gap.
When the Westfold village is being attacked by the Hill Folk there seems to be only one horse in the village; as these are the people of Rohan ("The Horse Lands") we can assume the fighting men & their horses are away but where are the rest of the horses? There should be mares, foals, yearlings, & older horses no longer fit for fighting quite near to the village (there is a corral clearly visible in the village).
Aragorn's sword disappears from his hand shortly before he falls off his horse, but reappears in its scabbard later.
The gash on Merry's face changes sides throughout the movie. Sometimes it is on his left brow, sometimes on the right.
As women and children enter Helm's Deep's caves, a rock stalactite swings back and forth after an extra touches it.
When Legolas is about to slide on the shield, his bow disappears when it shows the shot of his legs, yet in the next shot his bow is in his hand
Near the end of the film, when Frodo and Sam are in Osgiliath, the chain around Frodo's neck with the ring on repeatedly switches between being caught around one of his buttons and hanging freely between shots.
When the Rohirrim surround Aragorn, Legolas and Gimli and Éomer starts talking to them, the sunlight changes direction and intensity.
In Aragorn's memories of hugging and kissing Arwen, his left hand is alternately on her face or around her waist between shots.
While everyone was amazed by Legolas' skill in firing three arrows in quick succession whilst sliding down the stairs on an Uruk-shield, you can clearly see that each shot is cut when he is about half way down the stairs, i.e. he only had time to fire one arrow.
When Saruman is talking to the Uruk-Hai, they are obviously screaming and yelling, but there is no noise coming from them.
When Frodo, Sam, and Gollum are in the Dead Marsh and the Nazgul flies over, Frodo goes after the ring with his left hand, which Sam grabs and holds. Frodo is then shown putting his right hand to his chest, but in the wide shot, his right hand is still lying at his side.
In the scene where Treebeard the ent is carrying Merry and Pippen through the forest explaining to them about the lack of Ent-wives, the location of the branches around his head keep moving. Either they are from the side of his head and his shoulder, two out of his head, or none at all.
When Legolas is pulling Gimli and Aragorn to safety using the rope during the battle of Helm's Deep, Gimli is on Aragorn's right side for every shot except the first close-up of Aragorn in Gimli, where he is clearly on Aragorn's left.
A small gas pipe, leading to one of the large torches outside the Golden Hall, is briefly visible in some scenes in Edoras.
In the beginning of the movie, when Frodo and Sam are walking on the rocky mountain their rubber artificial feet can be clearly seen flapping around.
In Helms Deep, as Legolas throws the shield onto the stairs, he has his bow in his left hand. As he runs to jump onto the shield, the bow is gone. As he is sliding down the stairs, he is using the bow again.
When Legolas is waiting on the wall for the Urak Hai battle to begin at Helms Deep his hands repeatedly change position on his bow between shots.
When Gandalf and Theoden are talking outside town, near the burial mounds covered in white flowers, all the shots of Gandalf show the wind whipping his hair around, but in all the shots of Theoden there is not even a hint of a breeze in his hair.
When Theoden the king grasps his sword, Gandalf's grey coat is not on the floor at the wide shot.
When the three ladders are raised on the Keep in the Helms Deep sequence, the wide and close-in shots alternate between the outer two ladders being about 30 feet apart and less than 5 feet apart, respectively (the third is in between them and never makes it up).
When everyone is traveling to Helm's Deep, Gimli is riding on a horse. The head of his axe changes positions (blade down, blade up) several times when his is talking to people.
When Saruman tells the Orc to send out the Warg riders, his staff is in his right hand. In the next shot it's in his left hand.
When Aragorn first comes to Helm's Deep, the cut on his shoulder disappears during the sequence when Theoden tells Gimli that he can defend his own keep.
When the orcs are carrying Merry and Pippin on their backs the wide shots show the orc carrying Pippin to be closer to the camera with the orc carrying Merry to his left. But in the close-ups they have swapped places with Pippin having to turn to his right to speak to Merry.
When Pippin crawls toward Merry to talk to him, Merry is laying on his back. In the next shot, only one second later, he is laying on his side.
When Éomer and company ambush the Uruk-hai, we see Pippin as he is almost trampled by a horse. When the shot cuts to Pippin, his arms are unbound and free as he moves to defend himself. When he rolls away, however, his hands are bound.
During the trek to Helm's Deep, right after Gimli's horse runs off and he falls from it, Théoden turns to Aragorn and begins to speak yet no sound comes from him.
In the battle at Helm's Deep, when Aragorn unsheathes his sword, the shot is reversed (he draws it left-handed when he is right-handed).
Very near the beginning of the Extended version, some of the real fog in a valley visible at a distance behind Frodo and Sam abruptly disappears. While some close-ups were filmed in studio, it is also possible that there was a delay in filming these "on location" shots.
During the scenes of the capture of Gollum there is a breeze blowing Sam and Frodo's curly hair and surrounding grass clumps. Gollum's long stringy hair hangs straight and unmoving.
When the Warg riders attack, Legolas shoots them with arrows and then jumps on Gimli's horse riding behind him. In the next shot, Legolas is in front of Gimli on the horse.
At the beginning of the battle at Helm's Deep, the people in the fortress are seen drawing their arrows before one of them is accidentally released. Soon, they are seen drawing their arrows again, despite the fact that they should have still been drawn from the first time.
From the moment the Elves arrive (before the Battle for Helm's Deep) to the end of the battle, Legolas' armor covering his shoulders changes a couple times from leather straps to metal plating.
In the very first scene of the movie, the flashback from The Fellowship of the Ring, when Gandalf has his confrontation with the Balrog, Frodo yells "NO" before Gandalf falls, but in FOTR, Gandalf falls and then Frodo yells "NO".
When Gandalf, Aragorn, Gimli, and Legolas are leaving Fangorn Forest Gandalf is wearing an Elven cloak and brooch. Gandalf was not in Lothlorien when the others received their cloaks and brooches.
When Treebeard is talking to Merry and Pippin at the Entmoot, the stars that can be seen behind him change.
When Aragorn is tracking the hobbits beside Fangorn forest, his ring is on his right hand. Later, when the "White Wizard" is approaching the ring has switched to his left hand.
When Eowyn is traveling to Helm's Deep, her hair hangs loose around her face. About the time she arrives at Helm's Deep, it is suddenly pulled back on each side.
During the battle with the Warg riders, a Warg and Orc fall across Gimli. Visibly struggling to lift them off, there is no change in effort or position when a second Warg puts its weight on Gimli. This should be an addition of several hundred pounds.
When Aragorn, Legolas and Gimli are first introduced to Gandalf the White in Fangorn forest, Gandalf replies "yes, Gandalf, that is what they used to call me, Gandalf the Grey" when Aragron mentions his name. In reality, Gandalf would already be aware of his name as Treebeard had previously delivered the Hobbits Merry and Pippin to him, who would have obviously called him Gandalf when they met him.
Merry and Pippin switch position between shots when Merry is making his speech to Treebeard at the Entmoot.
In the initial shot when Theoden is talking to Gamling on the wall outside Helm's Deep, Gamling's mouth is moving like he's replying to Theoden's orders but no sound is heard.
When the Merry and Pippin are first seen being carried by the Uruk Hai, they are behind each other. In the next shot they are being carried beside each other.
Gamling's cloak is alternately over his shoulder and behind his back between shots as he is being instructed by Aragorn.
When Saruman tells the Orc to send out the Warg riders, a couple of seconds later the Orc's lips are moving in a reply, but no sound is heard.
When the Uruks are first introduced in the movie, we see all of them standing in one place for a split second and then they begin to run.
When Aragorn, Gimli, Legolas, and Gandalf first enter the Golden Hall of Edoras, Legolas is supporting Gandalf with his arm. When the door is shut behind them he lets go and in the next shot their arms are together again.
In the Extended Edition, when Merry and Pippin find Saruman's food storage, You can hear Merry whispering "Saruman's store," but his lips do not move when he starts to say it.
When Gandalf is riding Shadowfax "bareback", there is clearly a saddle under his robes and his feet are obviously in stirrups. In some frames it appears to be a Western saddle, because as the robes flap around it, Gandalf and/or his stunt double appear to hold the horn.
When Frodo is sliding down the hill outside the Black Gate he has a pack on his back but when he covers Sam with his cloak the pack is gone
During the battle of Helms Deep, when Legolas starts fighting with his knives you can clearly see there are no arrows left in his quiver. Later in the battle he's shooting arrows from his bow again.
When the Uruk-Hai are approaching Helm's Deep, they sound like all of them are marching in complete lock-step, even when they're marching on uneven terrain and around obstacles.
In the dream sequence with Aragorn and Arwen, after Arwen says "Then, it is a good dream," there is one shot where her hair covers both ears completely. All the rest of the shots have both ears plainly visible.
Near the end of the battle for Helm's Deep, Theoden, Aragorn and others are waiting for the Orcs to break through the door. In the next shot they are on horses charging toward the Orcs. There were no horses around to begin with.
During several close-ups of Gandalf, like the scene in Théoden's hall, you can clearly see he's wearing contact lenses.
After the Rohirrim surrounding Aragorn, Legolas and Gimli are about to leave, you can just make out Eomer's sword falling out of its sheath. It can be seen in the next shot.
When Sam is telling Frodo to use the ring to escape Faramir, the light changes directions (from the left in the wide shot, from the right in the close-up).