As per Nintendo themselves:
"Nintendo reported today that the game sold more than 1.2 million* total units across Japan, Europe and the Americas during its first weekend on the market"
Why is there even a debate about whether this is shipped or sold? The press release is identical to the announcement that Pokémon X & X sold more than 4 million during its first weekend on the market.
http://purenintendo.com/2014/06/02/nintendo-pr-mario-kart-8-sells-more-than-1-2-million-units-worldwide-over-first-weekend/