In any case, a handful of gamers in Japan are reporting problems, and there have been instances in which the software won't even start up. We wouldn't worry too much over the issue, though. Theoretically, if Brawl works with your Wii, Mario Kart should too (even though it's not the same dual-layered disc issue). If you haven't tested out Brawl on your Wii yet, though, you might want to cross your fingers come launch day.
Have any of you readers who've already purchased the game experienced any problems?