Revealing mistake: In the last midtro for level 18, "Mount Doom, " Sam reaches down to pull Frodo up the edge of the walkway. Sam's hand is seen to the top right of the screen, but a good chunk of it is missing.
Bug: Return Of The King, Level 4: The Battle Of Pelennor Fields - The orc army is approaching Minas Tirith at the start of the level clip. But as the "camera" pans around, half of the orcs literally disappear.
Trivia: When Elrond is welcoming Frodo into Rivendell, a LEGO character can be seen in the background wearing a black suit and tie. The character is none other than Agent Smith from The Matrix. Agent Smith from The Matrix and Elrond were both played by Hugo Weaving.