The G moneybag on the cover of Fortune Street reminds me of the ones from Shake It:
Not sure if this truly qualifies, it could very well be related to Dragon Quest instead for all I know, but it's at the very least a similarity.
Well half and a half, they said that Charles Martinet isn't the first voice of Wario, which is true.
But this version of curious facts is more reliable:
According to this, Wario was planned to make a second appearence in a New Super Mario game.
An actual feature was dropped, enjoy your decorative reward!
Wario in Mario Kart Arcade GP DX has a boxing glove contraption, very similar to the one he has as Genius Wario in Master Of Disguise, as his special item:
Did we ever mention Mario's Super Picross?
Cause I'm sure this background looks familiar:
It's all Wario's powerups from the first game!
http://www.spriters-resource.com/snes/marionosuperpicross/sheet/60526/
The Nintendo edition of Monopoly has three notable Wario things:
Clearly just the Wario World cover without the man himself.
Screenhots of Wario fighting Dual Dragon and Wario in Beanstalk Way respectivly, the former is on the board, while...
I really don't know if it's already said since this threat is totally huge.
But Wario do a little appearance (along with other Nintendo characters) in the audience of the King Dedede fight in Kirby Super Star Ultra.
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Starfy 3 has a remix of the Wario Land 3 theme:
And Wario's Amiibo theme in Mario Party 10 is a remix of Stonecarving City:
Big kudos to CM30 btw, for beeing probably the first one to upload this on Youtube, it's been nagging me ever since I...
This Wario from the japanese Wario World cover:
can be found on these flags in Superstar Baseballs Wario Palace:
(Not the best pic, but this one was a pain to get as it is)
Turning Wario into Gold Wario on Smash 3DS's Golden Plains stage...
Wario appeared in an very early demo of the canceled Diddy Kong Pilot:
The design of his plane might also be partly inspired by the Bulldog's design in Land 3 :
Speaking of which, the design of the planes in the Kamek boss minigame from...