yeah, my list is just the characters in the final medley
I also have to add Sherlock Hemlock, and Rizzo the Rat
Some other things I noticed:
Lewis Kazzager can be seen in 2 scenes, the first being when Kermit says "Hark, me thinks me hears carolers" and the second being when Mrs. Bear is explaining why Gonzo and Animal are on hooks
Also, if you look close, you can see the arm of the performer doing the Muppaphone, wearing a black sleeve
When Rowlf sings "some things change with passing years" you can see that the cow puppets are just heads, without the rest of the cow
Animal isn't in the medley, but right after the song ends and Kermit tells Piggy that he has a present for her, if you listen closely, you can hear someone who sounds like Animal yell "Ow"