The Lord of the Rings: The Return of the King

Factual error: 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.