Corrected entry: In the scene where Sam is chasing Frodo into the river, there is a shot of Sam sinking in slow motion. However, you can see that the water surrounding him is murky with sand. That proves that his feet are touching and kicking the bottom.
Corrected entry: In the scene where Arwen first appears she has her hair loose. She talks to Frodo in elvish and you see a close up of his face, then the camera goes back to her and her hair is all in little plaits.
Correction: Arwen's whole appearance changes in this scene - hairstyle, clothing etc. At first (as she is seen from Frodo's POV) her true appearance as an Elf is revealed - white, shining, perfect - and then it changes to show her in her riding clothes, looking more normal. The book refers to this happening with Elves on a number of occasions - and once or twice even with Aragorn.
Corrected entry: In the movie, Bilbo's book is called "There and Back Again - a Hobbit's Tale," but in the book "The Hobbit," it's "There and Back Again - A Hobbit Holiday." Maybe Peter Jackson thought audiences would misinterpret Bilbo's British use of the word "holiday"?
Correction: At the end of 'The Hobbit', when Bilbo is writing his memoirs, certainly it is stated that 'he THOUGHT [my emphasis] of calling them 'There and Back Again, a Hobbit's Holiday' ' - however by the end of the 'The Lord of the Rings' this has changed significantly. When Frodo has finished writing his part of the tale, he hands the book on to Sam for completion (last chapter, 'The Return of the King'), and Sam sees that 'the title page had many titles on it, crossed out one after another, so: My Diary. My Unexpected Journey. There and Back Again. And What Happened After. Adventures of Five Hobbits. The Tale of the Great Ring, compiled by Bilbo Baggins from his own observations and the accounts of his friends. What we did in the War of the Ring. Here Bilbo's hand ended and Frodo had written: The Downfall of the Lord of the Rings and the Return of the King. We can hardly blame the film-makers for avoiding all that and just keeping it simple!
Corrected entry: There are two parts in the film where Sam refers to what "Gandalf told him". When he first tells him (in the cornfield) he says "Don't you lose him Samwise Gamgee", but at the ending (right after Frodo saves Sam from drowning) he says, "Don't you leave him Samwise Gamgee."
Correction: How is this a "mistake"? Sam could have remembered what Gandalf told him two different ways; memory is a very subjective thing. Or he could have chosen to use the word "leave" rather than "lose" the second time because it had more impact. Or he could have decided that even though Gandalf had said "lose", what he truly meant was "leave". There are a dozen other plausible reasons for this.
Corrected entry: After Frodo pulls the ring off for the last time, he falls off the stone ruins, and lands on his back. He then immediately jumps up, having no reaction to his fall. It seems like after falling a distance of about six feet and landing flat on his back, he'd need a minute to recover from the wind being knocked out of him, or hitting his head. (01:16:55)
Correction: He's a bit hesitant getting up, and panting, plus we've been told many times that Hobbits are sturdy creatures.
Corrected entry: In the fellowship of the ring, when we first meet Legolas he has brown eyes. In the next two films the colour of his eyes alternate between being very dark blue, to icy blue.
Correction: Arwen's eyes change color too, it's an Elvish characteristic.
Corrected entry: When Gandalf first approaches the village on the cart, a water-powered mill can be seen slowly turning in an anti-clockwise direction. The water in the foreground stream appears to be travelling from right to left which would make the mill turn in a clockwise direction. However, in the very next scene (shot looking across the bridge at the same mill) the water is clearly stationary because the leaves on the surface of the stream are not moving. So either the mill is turning the wrong way or it should not be moving at all.
Correction: If you look closely at the mill house, you can see a water sluice over the top of the wheel. It is the water from the sluice which is turning the wheel, not the water in the river. In fact the wheel doesn't even touch the river.
Correction: Some people have said that as the scene was shot on a dry soundstage it's not a valid mistake, but that doesn't change anything - they should have used clear water when adding the effects later. EXCEPT other people have pointed out that he could easily be kicking the bottom and still drowning - he can't swim, and is loaded with heavy equipment to boot.