Sonic and Mario can't have hidden messages in them, can they? Well, there was the famous (infamous) "U R MR GAY" scandal, with the Photoshop sparkles on the official boxart (look at your own copy if you don't believe us)picking out specific letters on the Super Mario Galaxy box art.
But Mario's not the only one said to 'drive on the other side of the road'. Listen to the Sonic trailer for Super Smash Bros Brawl played backwards:
Surely it wasn't done on purpose, surely. In a less controversial observation, it seems there's a secret nod to Mario in the very first Sonic The Hedgehog:
Deliberate cap-tip to the plumber, or just two lions standing up against a pedestal (that handily makes for a nose, eyes and moustache)? We reckon it's the former.
While we're on the subject of Sonic, there's a reference to a 'one-eyed snake' in the Sonic cartoon, too. Strange choice of words, Bunny.