Let me preface my question, by saying that I understand that learning Japanese from anime would be like learning English from Bugs Bunny. I get that people in Japan don't speak like cartoons...
I notice in anime when there is a foreign character speaking Japanese, they tend to have an "arisu" or "aru" at the end of their sentences. For example, in Hetalia, China ends his sentences with "aru" and in Himawari!, one of the half American characters consistently ends everything with "de arisu". Out of curiosity, why is that? Is that a mistake that pops up a lot when foreigners are learning Japanese (kind of like you hear a lot of issues with subject-verb agreement when some people are learning English) or is there another origin? Just wondering...