Super Mario Kart
Ghost Valley 2 is the second course in Flower Cup. This course is similar to Ghost Valley 1, having walls in most places (and the blocks that make the wall can also fall still). The background is basically the same also, having Boos again. While it contains a Zipper at the end of the course, it's very difficult to use and is recommended only for advanced players, because it's positioned right after a curve at the edge of the track. Preceding this zipper, there's a jump line with an Item Box behind it. The Cape Feather is put to extremely good use here, as it can help the player jump over the gap at the beginning of the course whilst other players just take the standard route round (where the two single Item Boxes are).
Mario Kart Wii
In Mario Kart Wii, a remake of the course is included just as one of the four Retro tracks in the Shell Cup. However, because the Cape Feathers didn't exist post-Super Mario Kart, a ramp was positioned there to help out. Tricks must be done to get to the other side, however.
Because the original is pure-2D, Nintendo had to remake the entire course in a 3D environment. The Boos in the background became 3D, most of them disappearing and then reappearing again. Some even seem to be on the track, unlike the original where they stayed in the background. The walls became 3D, originally being flat blocks. The Zipper at the end is easier to get to without falling off, noting that the handling in this installment is much easier than that of the version in the SNES installment.
The music wasn't changed, apart from being upgraded to Wii-standard sound quality.