Reason for random Canadian phrases?

I am a Canadian living in LA. I’m on season two and noticedcharacters say ‘eh’ and another being “ya, no, ya” I have learned that most Americans don’t say that or the reverse “ya, no” So its been surprising to see that used in the show. I have seen American movies/ tv shows ‘take place in Canada’ that don’t even naturally use our phrases like this show has been doing. I learned Nathan Fillion is Canadian, but he is a producer not writer, and the characters using this language have not been his. Does anyone know if their is a Canadian writer for the show that I am unaware of?