Atari reference
Go to the Arcade level and look at the background. If your camera view is on the right side, you should see a person whose back is towards you. He will be playing on one of the machines. He will have the Atari symbol on the back of his shirt.
Make opponent's Wiimote talk
In Multi-player mode, go in any game with you and a friend. At any time during your opponent's turn, press any direction on the D-pad. Their Wiimote will then say "Jenga" in different tones every time you do so. This is a good way to distract or annoy them.
Never-ending earthquake rumble
When playing a game with power-ups and you get the earthquake, try to take out a block. When you are getting ready to place it down, drop it when the earthquake is still rumbling. If done correctly, the rumbling of the earthquake will not stop until you get to the game menu.