The ghost walrus is Smokey.
Maybe he died not long after meeting Minnie, having been on drugs for far longer than her. He was stuck wandering the earth as a ghost, watching Minnie and seeing that she wasn't doing any better. So he met with other ghosts, and they all agreed to work together to confront anyone who might be trying to live the same life that he and Minnie lived, and scare them straight.The jury is out on whether Smokey Joe actually was an anthropomorphic walrus in life, or if he just became one when he became a ghost.
It's a shame that we never got a cartoon based on "The Ghost of Smokey Joe
". Then we would know for sure.
Minnie is not still alive, as the above theory suggests.
She's the witch-like ghost who appears near the end.Alternatively, Minnie is the walrus herself.
Maybe In-Universe, she's a woman who just has a rather deep voice for a woman. Hey, we don't know for sure that the walrus is male.