So I have a character who is a native German speaker going to college in America. He's mostly fluent and knows some slang (because I am sure he's watched American movies and TV, and he's been going to college at this point for three years). Are there any common grammatical mistakes he might make or words he might mix up? I know, for instance, from my many years of taking French, that native French speakers tend to give words a "the" when a native English speaker wouldn't, or end a question with a yes/no ("You enjoy the tennis, no?"), because that's how it works in French and they're making a literal translation in their head. (And I know I make similar mistakes in French, though I have no idea what they are.) But since I've never met or had a prolonged conversation with a native German speaker, I have no idea what sort of verbal irregularities they might have besides an accent.
Help? I don't even know how one would hypothetically google this puppy.