With Roscoe/Gordon that's not surprising, since he's been a staple on the street ever since his Matt Robinson days, but interesting that Leela will make an appearance since we haven't seen her of late outside of repeat episodes. I can't wait to see this special.
They should reference that. It would be nice to hear the Elmo of today meet some of the early Elmo's (Brian's, Richard's, etc.) with an explanation that maybe there were his ancestors or something.
I do disagree with one thing though. I think although Sonia is retired, she can at least make a come back for this special, same with Ruth Buzzi for that matter. After, all Bob Barker made guest appearances on
The Price Is Right after he retired. I know Casey Kasem came out of retirement to voice Shaggy's dad on a few eps of
Mystery, Inc. As J.P. from
Angels in the Outfield would say, "It could happen."