New Super Mario Bros Wii.

[retrolinkx]

On the disc of New Super Mario Bros, Mario, Luigi, and two toad's are on there at 90 degree angles, each having a specific colour relating to the SNES's controller colour layout.

Rec Mario being on the right, is the SNES's A button
The Yellow Toad being on the bottom, as the SNES's B button
Green Luigi being on the left, as the SNES's Y button
The Blue Toad being on the top, as the SNES's X button.

I thought this would be something interesting to point out.

[Psychospacecow]

Very interesting little throwback right there.

[DidYouKnowGaming]

I'm not convinced this is a throwback, but it definitely could be one. I'd rather know more about the reasoning behind Nintendo's choice in colour before I say this is a reference.

[Moriatti]

Wow! Never saw this coming! I probably should've, given that the Toad's head spots look like buttons!