In Oblivion, Ayleid ruins contain all sorts of modern and out of place items. Like Septim gold pieces when the Septim empire did not exist at the same time of the Ayleids. Or Dwarven weapons despite the Dwemer and Ayleids having virtually having no contact, and the fact that Dwarven items are supposed to be rare.
This would be like if an archaeologist went into an Egyptian tomb and found American dollars and an ancient Chinese sword lying around.
To make the Ayleid ruins accurate you should be finding an Ayleid currency and only Elven weapons in the containers and on enemies.
Probably, the biggest culprit to this random item lists and level scaling. Also, there are times where the designer places something without thinking.
Now this will probably be very low on the developer’s list of things to do but it would be a nice touch to the game.
If anyone knows of a mod that does this to Oblivion or Morrowind please post a link here.