That’s why Sonic has separate eyes and more human features, and why he’s an alien in the film. Because the choice was made to set this film in our world as we know it. Sonic the Hedgehog isn’t the first movie to take this approach when adapting a fantastical property to live-action (animation has more freedom to be strange in this regard). The Smurfs in 2011 and 1987’s Masters of the Universe come to mind as properties that took characters out of their fantasy worlds and plopped them in our Earth.