Oh c'mon isn't it obvious? The filler characters.
Edit: Finally they brought back something that I've haven't seen since Believe. Its where they quickly show pics of the arcs that have yet to come. Like in WE Are they showed Buggy, Kuro, Don Krieg, Alvida and Smoker…then Dragon.
And this is understandable, having Franky standing behind the Straw-Hats while they're doing their little thing, since hes new and we haven't seen him interact with the crew yet. Well watch 1:09 and watch Franky.
I've listened to 5050's Shonan Midnight Club and he obviously fluent in english. Well hes not making it sound like Engrish, his little rap was cool, I liked it becasue it had a simple rhyme scheme in it. Which is rare in most anime openings.