The should have shown how many cups are in the game, and what each item does, and what the menu system looks like.
Or, what they actually did was provide a focused, clear and concise look at what the game and system are about. Play Mario Kart, at home, on the go and with friends.
No need to over-analyse everything. Not EVERYTHING needs nitpicking criticism. It's a 30 second ad, some things are assumed.