I was watching the new season of Man on the Inside last night and caught two pretty substantial references to the Good Place in this scene. Charles is standing beside a notice board at Wheeler College, and behind him is both a Dance Dance Resolution flyer (Jason's dance troupe) and an Acidcat flyer (a DJ who wears a cat head, who Jason once stood in for). Whether this is just an easter egg or is meant to hint that we're in the same universe is hard to tell, but it does add a bit more to the sneaky Eleanor cameo from last season.
There's also a clip from an episode of Veronica Mars that shows up in the last episode, which suggests that Kristen Bell exists as an actress in this world, but is that a confirmation that these are just references and nothing more, or is it a way to throw us off the scent of a spin-off centered around Michael's life as a human?
I suppose we'll have to wait and see.
This would be an incredible ending to the show but I wonder if this is more about adding references for loyal fans of Danson and Schur. I'm only one episode into season two but they also added Mary Steenburgen as his romantic interest, who's his wife in real life as well as castmate in shows like Curb Your Enthusiasm, with a joke like "you look really familiar."