On almost all digital content there's a PAL vs. NTSC region restriction. USA is always NTSC , and SA + europe is PAL . So yea you will most likely have issues....it should actually state on the box whether it is PAL or NTSC . You can safely assume if it does not say PAL/Region 2 then it won't work without "intervention" on your Wii console.
My Xbox games all have a little "PAL" indicator right on the front of the box [top right] , i'm sure the Wii game will have it too.