Traffic is the greatest threat here, making it almost impossible to guarantee successful attacks on other racers without being much closer to them than usual. During Battle Mode, traffic on Toad’s Turnpike travels in both directions. Look out for racers lurking in between cars!
The walls here are good for escaping the chaos on the roads, but you’re not much safer on the walls if someone follows you! The two wall sections are small enough to be very problematic if items are cut loose there.