Listen to The Goodbye Song. Then ponder upon the fact that Lynne Thigpen, the VA of Luna, passed away of a cerebral hemorrhage in 2003. After that, wipe those tears off your eyes, listen to Bear's ending speech, and when he ends with a "see you soon", remember that the show has actually been off the air for years.
A Beary Bear Christmas has the song where Tutter sings about what it would be like if he was homeless like the dog he had just seen on the streets. Also, according to Word of God, the writer of the song originally intended for the song to be mainly performed by Bear and not Tutter.
After Lynne Thigpen died, Noel MacNeal gave a speech at the celebration of her life. Here's an excerpt:
When Lynne read the part of Luna with me, that was it. She was perfect, all the warmth and comfort and nurturing you'd expect from the moon. [...] She never saw this as just another job. She loved playing Luna and knew how so many children and adults loved Luna. Once on the set of The District, a crew guy found out Lynne was Luna and asked if she'd mind talking to his kid. And of course she didn't. He handed her the phone and I can only imagine the kid's expression knowing that Daddy was on location with the moon.
They Wasted a Perfectly Good Character: There were a number of regular guests that they probably could have developed more or even become regulars, but on the whole they generally stuck with focusing for the most part on the main cast.