Bob Dermer, the puppeteer and voice for Sam, also worked in the 1970s series Readalong and the long-running CBC show Mr. Dressup. He was also the voices of Ralph from The Raccoons and Grumpy Bear in the 1980s adaptations of Care Bears.
Nina Keogh, the puppeteer and voice for Muffy, also worked on Readalong. She also did work on Polka Dot Door, The Friendly Giant and Mr. Dressup.
Valdy makes a special guest appearance at the end of "Trash."
John Stocker, probably best known as the voice of Beastly in the Nelvana version of Care Bears, guest stars as sneaky night manager Crandall J. Crummington III in "Sam and the Robot".
Jeff Hyslop has had several TV and film roles since the show ended, but he's mostly been active in the theater. If you grew up watching this show, it can be a bit jarring to see the guy who played Jeff the mannequin playing The Phantom of the Opera onstage.
Nerene Virgin has had a few TV roles as well, although she's been more active as a CBC newscaster in recent years.