The song played in the end in the credits by Man Duck was a jazz version of Ð'ÐµÐ»Ð°Ñ ÐÑEUÐ¼Ð¸Ñ, ÑtÐµÑEUÐ½Ñ<Ð¹ Ð'Ð°ÑEUÐ¾Ð½ ("Belaya Armiya, Ciornij Baron"), one of the oldest Red Army choirs. I have no idea why. Correct me if I'm wrong.
The blend of styles was very bold and well done.
Claymotion, Jazz and that kind of free hand animation make everything a little disturbing and depressing. But I guess that was the desired effect.