Mario Kart Wii Cheat: A Theory

I've been reading about these "cheaters" with the ridiculously fast times.  I haven't played the game, but from what I've read, the low-timed game is done slowly.  This most likely means the "cheaters" are actually exploiters of a rollover glitch.  After the time reaches 59:59.99, perhaps it goes 00:00.00?  That doesn't explain why all three of the top scores were identical.  I understand those scores were removed, but unless Nintendo forces an update to the Wii, they'll just do it again.