Continuity mistake: Just before the trees start killing the Uruk-hai, we see the backs of Gandalf and the rest of the heroes on horseback as they're watching the forest. Gandalf is holding his staff up in his right hand. Next close-up shot, he's lowering the staff in his left hand. Extended DVD. (01:38:20)
Audio problem: When Sam, Frodo, and Gollum are in the forest of Ithilien, when Sam says "Can't you hear yourself, don't you know who you sound like?" the shots change and you can see Sam mouthing the words again. (01:38:30)
Continuity mistake: In the opening close-up shot of this scene just before Gollum says, "We wants it. We needs it. Must have the precious," Frodo and Sam are seen sleeping side by side. In the next wide shot of them they are sleeping perpendicular to each other. (01:38:35)
Continuity mistake: As this scene opens with an Uruk's body being dropped to the ground, the camera pans out to show Legolas and behind Gimli to his left, is a large rock. In the view from the front, now there is a dead Uruk sitting up against the same rock, where there was none before. He's dead, so he didn't move there between shots. Extended DVD. (01:38:50 - 01:42:55)
Continuity mistake: The bodies and rocks behind Gimli change positions, between shots. When Gimli says the words, "That's not bad for a pointy-eared Elvish Princeling," there is a rock right behind Gimli to his right. In his close-up it's not there. Yet, when the camera does another close-up, when he reacts to the arrow between his legs, the rock is to his right again. When Gimli says the words, "I myself am sitting pretty on forty three," behind him to his right, a Rohan turns over the body of an Uruk onto its back. When Gimli says the words, "He was already dead," that Uruk hasn't been turned over. (01:39:00)
Continuity mistake: In the extended DVD, when Gimli quips, "That's not bad for a pointy-eared Elvish princeling!" the back shot of Legolas shows him 'toying' with his bow, but in the front shot, his hands are apart holding the bow. (01:39:00)
Continuity mistake: In this shot, Pippin grabs some apples and a green ear of corn, then he puts it all into his left hand, starts to turn around and with his empty right hand he reaches for a floating cauliflower. The camera angle changes, and in the next shot, we see him holding an apple and corn in the right hand and another apple in his left hand. Floating to the right of him is no longer a cauliflower, but a green bottle. Extended DVD. (01:40:05)
Continuity mistake: At the end of the film, when the heroes of the big battle are watching the lightning over Mordor, while Gandalf says the words, "The battle for Helm's Deep is over", over Legolas' right shoulder is a far view of the Deeping Wall and the Causeway. There is no break in the wall, or ladders at the wall, nor are there any bodies anywhere on the Causeway or otherwise. (01:40:13)
Continuity mistake: At the flooded Isengard, the first shots of Pip and Merry are in front of Saruman's storeroom. Floating in the water, directly behind them are a large barrel and a large crate. In the shots of them turning to enter the storeroom, the floating barrel and crate are gone. Extended DVD. (01:40:15)
Continuity mistake: When Merry and Pippin first enter Saruman's storeroom, in the close-up, Merry is holding an apple and a large glass carafe with wine. As the camera pans out, to show the whole storeroom, he is no longer holding the large glass carafe, but he is holding an apple and a turkey. Extended DVD. (01:40:20)
Continuity mistake: Gollum brings two rabbits and drops them onto Frodo's lap. When Gollum takes one from Frodo's lap, in the close-up the head of the remaining rabbit is lying on Frodo's right leg. In the wide shot when Sam takes the rabbit from Gollum and pushes him away, the second rabbit is lying on Frodo's lap differently than the close-up. Also in the close-ups of Gollum we see the structure behind Gollum that has Sam's gear lying beside it. In the wide shots some of the gear is arranged differently. (01:41:05)
Revealing mistake: When Gollum brings the two rabbits, he drops them onto Frodo's lap, and Frodo is leaning up against one of the broken stone structures. After Frodo opens his eyes, the stone structure behind him vibrates when he moves a couple of times. This structure should be way too heavy to jiggle when Frodo moves. (01:41:05)
Continuity mistake: On the way to the old sewer in Osgiliath, in the first shot, we see Faramir leading Frodo and Sam with Gollum in the rear. In the next two shots, Gollum is directly behind Faramir now, with the two Hobbits reaching the entrance first. Extended DVD. (01:41:35)
Revealing mistake: Sam says "There's only one way to eat a brace of coneys" and in the next close-up, Sam stirs the stew. The rolled up blanket is behind the hanging pot, which means it's on Sam's right. In the next three shots, Sam's pack is behind the pot, not the rolled blanket, to Sam's right. Then, in the next close-up of the pot, it's the very same close-up shot as before, only it's been flipped, and the rolled blanket is there, near the pot again, this time to Sam's left. (01:41:40)
Continuity mistake: At the beginning of the scene, Sam is cooking the rabbits. Behind Gollum, Frodo's coat and pack lay on the left side of the overturned stone carving. In the following close-up, when Frodo goes over to his pack to take out plates and spoons, his coat is now on the right of the overturned carving. In the next wide shot, it's on the left again. (01:41:50)
Continuity mistake: While Sam is cooking the rabbit stew, Frodo goes to his pack lying beside the broken stone statue to take out the plates. In Frodo's close-ups the trees and bushes near the statue are positioned differently and some are even different than the trees and bushes in the wide shots. (01:41:55)
Revealing mistake: Frodo, Sam, Faramir and Gollum are at the sewer in Osgiliath when Faramir asks, "Cirith Ungol?" and then grabs Gollum's neck. Frodo and Sam watch as Gollum is grabbed, but their eyes do not follow Gollum as Faramir grabs him, their eyes remain focused on the ground to their left. The shot of Faramir and the shot of Frodo and Sam were edited together, with Gollum added later. (01:42:20)
Continuity mistake: In the extended DVD, right before Faramir lets Frodo, Sam, and Gollum go, he grabs Gollum around the neck. The problem is, he grabs Gollum from behind, so his hand is on the back of Gollum's neck. He then pushes Gollum up against the wall, but suddenly his hand is in the front. I've watched this closely, and there isn't enough time for Faramir to twist his hand around. (01:42:20)
Continuity mistake: Frodo lies down to look at the Southrons. Sam and Gollum come close, and crouch alongside him. In these first two shots, the ground beneath them is uneven, has patches of green grass, bramble, and some small green leaves near Frodo's fingers. After a cutaway, in the next shot of Frodo, Sam and Gollum, they are lying on even ground with yellow dry flat grass. Then Sam says, "No one at home would believe this," and the ground is now the same as in the first shot. (01:43:00)
Revealing mistake: When Gandalf, Aragorn, Theoden, Legolas and Gimli all ride up the hill on horses towards the end, there is a man on a horse on the left of the screen. Who is he and why is he there? He's Éomer's body double (Karl Urban was unavailable) and at some stage they were going to put Éomer's head on him digitally, but they never got around to it. Director's commentary, extended DVD. (01:43:05)
Answer: The movie makes it clear that Gandalf has lost some of his memory and his personality has changed. Gandalf actually did die and pass over to the "other side", as it were but was sent back to complete his task. However, he was sent back as a similar, but different entity. Gandalf the White does not have all the memories of Gandalf the Grey, at least at first. He doesn't even remember that he used to be called Gandalf the Grey until someone points this out to him. It is implied that Gandalf doesn't even remember Sam until Aragorn mentions him. Gandalf then searches his memories and remembers who Sam is and his eventual importance to Frodo's quest. When he finally remembers this, he is pleased that Sam went with Frodo, as he will play a crucial role near the end of the journey.