Continuity mistake: When King Theoden is lying under his horse, when Eowyn starts to battle the Witch King, he has spots of mud on his right cheek that are very clear. After Eowyn has slain the Witch King the spots on Theoden's face are now faint smudges. After he dies and she leans down to hug him, the spots are now as they appeared in the first shot. (02:09:20 - 02:15:45)

Continuity mistake: At the Grey Havens, just as Gandalf stands before his four brave Hobbits and says, "I will not say, 'Do not weep,' for not all tears are an evil," note the design on Pippin's scarf. When Gandalf says, "It is time, Frodo," the pattern on Pippin's scarf is entirely different, though it's the same style scarf. It then reverts back to the previous pattern when Frodo boards the White Ship.
Continuity mistake: In the previous movie Oliphaunts make sounds similar to real-life elephants. However, in this movie, they sound entirely different.
Revealing mistake: When Gandalf is riding to the top of Minas Tirith, watch the second level carefully. You can see a background character (I think it's a soldier) disappear twice as Gandalf rides past. (00:42:50)
Other mistake: After Gollum attacks Frodo and Sam on Mount Doom, Sam fights Gollum off with his sword. He then turns around and calls out for Frodo. There is a brief medium shot of Frodo scrambling up the mountain (at about 01:20:35 on disk 2 of special edition). If you look carefully in the background, you can see snow and running water in the background. This is common on Mt. Ruapehu, where the scene was shot, but a bit out of place on Mt. Doom. (01:20:35)
Answer: Aragorn is 210 years old when he dies. Some of the early texts give his age at death as 190, but Tolkien eventually confirmed that 210 is the correct age.
Tailkinker ★