I wonder how close to Jim Henson's death Mupet Vision 3D was made. Waldorf sounds like he has a cold in the film, but Kermit sounds alright. Scooter, however, sounds a bit more like Janice at times (of course the voice is pretty much the same, but there is also a slight difference).
In the pre-show, there is a character identified as Rick. Could he have been performed by Rick Lyon? I know that Rick Lyon performed in the movie, though I'm not sure of the pre-show, and I don't recognize the voice of Rick, and don't know what voices Rick Lyon can do. Maybe if you ever get to interview Rick Lyon you can ask him.
Interestingly, I thought I'd read that the penguin orchestra was referred to as Nicky Napolian and his Emeror Penguins, but I didn't hear that name used anywhere in the attraction audio (yes, I know that name was also used for the penguin band in Little Mupet Monsters, but I thought they were called by that name in the 3D film as well).