I was just thinking about Annie Lennox's song, "Into the West," at the end of Return of the King, and it has a rather big error that's been bugging me for days.
Across the sea
a pale moon rises
the ships have come
to carry you home
...It sounds very pretty, but the sea is to the west! The moon has to be setting! Unless of course it's in a retrograde orbit, which is not only difficult to maintain, but quite hazardous.
The other possibility is that the planet's magnetic poles flip-flopped between then and now, which it does occasionally. That would explain all the landmasses in the ME maps are different from the ones we know now ... the continents have not just shifted, they've gone ALL out of whack! (Tolkien maintains, after all, that LotR is something that happened "long ago, before the world changed.")
No, wait, that won't work. At the battle of Helm's Deep, Gandalf and the Rohirrim came from the east, blinding the orcs by having the sun at their backs. So therefore, the moon either rises over the mountains, or the song just has a big ol' continuity error.
Then of course, there's the fact that it's just a show, and I should really just relax.