What is meant by "RUS"?

The Rus were the peoples of an East Slavic culture based around Kiev and the Ukraine. Although the culture had its ups and downs, they often were influential in controlling the trade routes from the Meditteranean to the Baltic region.

I don't know about a King Arthur film, but something like it originated in the book and then film "The Princess Bride". There's an acronym that stands for 'rodents of unusual size'. It's in the swamp scene.

Maybe if you refer to the film you saw this could be researched.