The character of Vivian Gibson is a nod by the episode's writer A.J. Carothers (1931-2007). 'Vivian Gibson' was his real-life mother's maiden name.
Originally first seen in Episode # 20, but also seen here is the Douglas family basement. Rarely used thereafter, if only when dictated by the story.
Very strange how Cheryl Holdridge's character reacts when she sees Mike. She originally met him in Episode #5 but this time acts as though she doesn't even know who he is!
Paul Burke appears uncredited as Mr. Collins.