Audio problem: First there is a wide shot of the Dead Marshes and Gollum says, "Soft and quick as shadows we must be." Then in the next shot as the camera starts to pan towards Sam, he begins to say, "I hate this place, it's too quiet..." When the camera first shows Sam, his mouth is not in sync with these particular words, "I hate this place," the words originally said on camera were changed during ADR. Extended DVD.
Audio problem: When Gimli says the line "Helms Deep! They flee to the mountains when they should stand and fight! Who will defend them if not their king?", Legolas, Aragorn, Gimli and Gandalf are walking towards the stables. Gimli's lips are not mouthing any of the lines. This is because it is the scale double of Gimli walking with the three other actors and John Rhys-Davies added the dialogue in ADR later.