A Physics professor recently watched "The Return of the King" and he got to wondering how fast the beacon signals for (movie) Gondor should have been. In an interesting blog post, he tried to work out the math. See How fast is the Beacon of Gondor for the full post. People have left numerous comments (many of which contain errors of fact about Middle-earth and/or the book-version of events).
Some of the not-so-obvious things people missed in the books include:
Gandalf and Pippin rested during the day while riding to Gondor
The book mentions two lines of beacons; one goes toward Rohan, one toward Belfalas
The northernmost beacon is less than half the distance from Minas Tirith to Edoras
Mordor controlled many lands capable of supporting horses
As several of us noted in the comments on the professor's blog post, the movie was compressing time. It's not entirely clear (to me, at least) how much time was supposed to be passing in the movie. They cut out a lot of the story (including most of the background history).
[ 08-12-2010, 08:23 PM: Message edited by: Michael Martinez ]
-~-~-~-~-~-~-~-~-~-~- Author of Visualizing Middle-earth, Parma Endorion: Essays on Middle-earth, 3rd edition, and Understanding Middle-earth.