How do we know? It's all thanks to a custom Sega Genesis cartridge. IGN received a Sonic the Hedgehog 3 film mailer this week that includes a Sega Genesis cartridge that's actually playable.

Unlike traditional video game cartridges, it does not contain the actual game itself. Instead, it functions as a collector’s item packed with exciting features. Housed in a custom Sega Genesis ...

We've only had the one trailer so far, but to promote the upcoming second, Paramount has sent out a handful of genuine, functional Sega Genesis / Mega Drive cartridges ... in case you're wondering ...