At the begining of cycling when the numbers are going down, you can hear the same sound from the Mario Kart games when those numbers are going down.

When you fall off of a cliff in Cycling mode, you can hear the same sound from when you fall off a cliff in Mario Kark 64.

During 3-point contest (basketball), you may possible hear a "Wa-ha!" which sounds similar to the "wa- ha!" Mario says in Super Mario 64 after a Triple Jump.

In bowling when you zoom in you can hear the sound when you bring up the menu in Animal Crossing. (This is also in Wii Sports)