Height-wise, the scale's bothering me. The driver should be a lot higher up so he can see over the team of horses. Right now, those horses butts are only good view he's getting, and he's not gonna like it when, as horses tend to do, they drop a load.  He also can't see what's happening on gthe road behind him.  Especially, if they're carrying any luggage on top. Also, why not just make the driver's chair a bench? You'll have room for two drivers and that shouldn't get in the way of any camera shots.

Personally, I also think the carriage body itself is too low to the ground, and the axels of the front and back wheels need to be on an even level with the carriage riding above it. The wheels being the different sizes that you have makes the carriage look cool, but it's just not practical. That carriage should be tilting forward the way you have things now.