I am not completely sure but I believe that I heard Yaviks (aka the Rider) speking [b]russian[/b] during her boss-fight. She tends to shout a few lines when being attacked or boosting her pike, which sound extremely similiar to russian words for "[i]onwards![/i]", "[i]faster![/i]" and "[i]yes![/i]".
This makes pretty much no sense I think, unless Rider is somehow related to Rasputin maybe? I doubt that. Though it was funny noticing anyway!
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Russia has played a role in the whole game, though. The Earth locations of D1 are in Russia, which means signage and leftover culture around us on Earth are Russian themed. Rasputin is Russian. Why would it be weird for some characters to know Russian?