His hair is correct for the period
So I think Daniel's haircut is correct for the period - I saw a lot of comments saying it was wrong.
If anyone has seen Boardwalk Empire, which is also set in the Prohibition Era, most of the men have the same haircut: shaved on the sides, longer and slicked back on the top.
Apart from that, I DO agree that he has the vibe of 21st Century hipster... :)