Continuity mistake: While looking at the Haradrim, in this first front shot Frodo says, "We've got to get moving. Come on, Sam," Frodo starts to back away and rise. Sam grabs his hand and pulls him, saying, "Mr Frodo," and Frodo's position is farther behind Sam. In the next back shot Sam and Frodo are lying evenly, side by side. Then in the next front shot as Sam says, "It's an Oliphaunt," Frodo's position is behind Sam and he is crouched higher than him too. (01:43:45)
Revealing mistake: Shadowfax, the horse that only Gandalf is supposed to be able to ride, will not take a saddle and bridle, so throughout the majority of the film, they try very hard to hide the saddle that Gandalf is obviously sitting on, even though you can see him holding the front of it underneath his robes, and sometimes, you can see him holding a very thin bridle. But right at the end of the film, when you have the shot of Gandalf, Aragorn, Legolas, Gimli, etc. on horseback, you see Gandalf's feet in stirrups. (01:44:05)
Continuity mistake: At the end, it shows Sam and Frodo walking through a forest. The very first shot of that scene shows Sam saying, "I wonder if we'll ever be put into songs or tales." In the background, through the trees, you can see the city of Osgiliath. Then it shows Frodo, with Sam in the background, and Frodo asks, "What?" In the next shot they are way further into the forest and you can not see Osgiliath. (01:44:40)
Continuity mistake: Faramir hits one of the Haradrim riding the Mûmak with an arrow and he falls. As he hits the ground, in the background are Frodo and Sam. Sam's cloak is not draped over his left shoulder in this shot. In the very next close-up, Sam's cloak is draped over both shoulders. (01:44:55)
Continuity mistake: Faramir captures Sam and Frodo. Faramir goes over to the dead body, and says, "His sense of duty was no less than yours, I deem," and rolls over one of the Haradrim with his foot. The dead man is lying with his face towards the ground. In the earlier shot, when he fell off the Mûmak and landed behind Frodo and Sam, the right side of his face is lying on the ground. It is the same man in both shots. (01:44:55 - 01:45:40)
Continuity mistake: Having seen the attack on the Haradrim, Frodo says, "Come on, Sam," and he is seized by one of Faramir's men. In the next shot, Sam is getting up off his right knee, that having been the place where they were lying and hiding to see the Haradrim and Mûmakil. The edge shown in this shot has green plants growing alongside, and the bush to the right of the edge is also very different than earlier shots. This edge does not look anything like the two different edges shown, in the earlier shots of them leaning over. This is now the third edge being offered. (01:45:05)
Continuity mistake: Faramir and his men capture Frodo and Sam, and Sam is thrown to the ground. In these shots, Sam's cloak is lying straight under him, as can be seen when he says, "Wait. We're innocent travelers." When one of Faramir's men grabs Sam's shirt to pull him up, his cloak is lying on the ground, up near his shoulder out to his right. Sam has not moved, Faramir's man had a blade to his throat. (01:45:15)
Other mistake: When Faramir and his men are looking at the map of Middle-Earth in Henneth Annûn, you can see that the plain of Dagorlad is actually spelled Dagorland on the map. An odd mistake, especially considering the fact that they got it right when they spoke of it in the first movie. (01:45:20)
Continuity mistake: After seeing the Mûmakil, Frodo and Sam are captured by Faramir's men. In the close-up shot as Frodo says, "We are bound to an errand of secrecy..." he's being held by one of Faramir's men around the shoulders and Frodo is holding the man's forearm. A second man is close to Frodo's left whose right hand is down. In the very next wide shot Frodo is holding the man's arm differently and the second man to his left is not only further away, he's standing differently and grasping the hilt of his sword in front of him. In the next two close-ups of Frodo, he's holding the man's arm exactly the way he was in the first close-up. It's also obvious in the wide shot that it's the scale double of Frodo. (01:45:25)
Continuity mistake: In Osgiliath, when Sam suggests that Frodo should use the ring to disappear, not only has the background changed, as has already been noticed, but Sam quickly changes position when Faramir enters. He is not left of Frodo anymore but right of him (seen from the viewer). (01:49:13)
Other mistake: John Noble's name is misspelled in its second appearance in the SEV credits. It is correct in its initial appearance (the fades with the fancy font). However, in the short list of where the actors are listed with their character's name, it is spelled "John Nogle." (01:50:50)
Other mistake: In the Fan Club Credits (Extended DVD), Cate Blanchett's name is spelled wrong. Her surname is spelled 'Blanchette' in the fan club credits. (01:53:25)
Continuity mistake: What happened to Aragorn's wounds on his shoulders after his fight with the Wargs? When he talks to Theoden on the outer walls of Helm's Deep, the blood is pretty much gone, only the fabric is stained. Later, when he and Legolas have their little heated discussion about the defenders of Helm's Deep, the blood is back again on the skin. (01:55:00)
Continuity mistake: After Haldir is struck in the back by an Uruk he falls to his knees dying. Aragorn runs up and grabs him but sees the elf is dead after his head falls back and lowers his body down before running off again. But he lets go of Haldir just above the ground and instead of just falling the rest of the way down the supposedly dead elf lowers his own head to the ground. (01:57:55)
Continuity mistake: Elves, as can be seen all through the battle of Helm's Deep, carry their sword and arrows on their backs, protruding some distance above their shoulders. When the elves arrive at Helm's Deep, however - none of them appear to be carrying a sword (it is possible that the sword could be sheathed at the waist, under their robes, but it seems unlikely that they'd change it to a back-sheath later on), nor do they have any arrows for the bows that they are carrying. (02:04:25)
Revealing mistake: In the shot after Gimli shouts "Send them to me" at Helm's Deep, you see the elf closest to the camera fire an arrow. As he reloads, his right forearm passes though the bowstring. (02:09:05)
Continuity mistake: When the Uruk-hai are sending the three huge ladders up on to the Keep, watch the last one just before Legolas cuts the rope that is pulling it up. The ladder has just passed the 90 degree/vertical point. Naturally, after that it starts gaining speed as it falls. Then it cuts to Legolas, who waits a second or two before firing his arrow. That would be plenty of time for the ladder to pass the point of no return, and hit the wall, so it would not have mattered if Legolas had shot it or not it would still have reached the Keep. (02:27:10)
Continuity mistake: As Theoden draws his sword before the cavalry charge from the hall, there is a rider to the right of Legolas at the edge of the screen. When it changes to a wider shot, the horse and rider are no longer there, and there is a clear space where they were standing. (02:31:48)
Audio problem: When the Ents are attacking Isengard, just after the river has been released. Merry calls to Pippin "hold on!", but if you look at his lips, he says "Hang on!" The lip-syncing doesn't match. (02:35:25)
Continuity mistake: When Sam jumps at Frodo in Osgiliath when Frodo confronts the Nazgul, they both fall down some stairs. These stairs, seen from the top, have a wall to their left and are open to their right, where the camera is positioned. When they are falling down the first few steps, you can see their feet pointing towards the camera, in the next shot a few steps down it is their heads. (02:37:06)
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.