The appearances that I know of are as follows:
#50 Leo Sayer: he performs in Leo's closing number "When I Need You"
#52 Gilda Radner: he sings in the opening number "Lullaby of Broadway"
#73 John Denver: he appears at the end of the Swedish Chef's act, where he chases the chef away with a meat cleaver
#86 Phyllis George: he wins the Fred Award for "Funniest Comedy Performance By a Bear"
#114 Marty Feldman: he's one of the 3 Bears/Thieves in "Ali Baba and the 3 Thieves"