Blue Shells can now be held behind you like Red Shells. They will explode on contact, but not hurt the player. They can be used to protect against other items being shot from behind, but if wheelie-bumped while holding a Blue Shell behind you it will fall away and disappear. Only one Blue Shell can exist at once, so even when it is held out behind you it will be impossible for anyone else to get one from an item box.
When in online play, the player's character, vehicle and drift mode choice may be changed between races by pressing + on the Wii Remote (or Start on the GCN Controller) when on the VR screen. This simply takes the player back to the character select menu, and then returns them to the vote when they have reselected. If the time limit expires, the currently selected options are taken.
You will see your speed in km/h units on the milliseconds section.