Concerning the death of Gerald Mohr, he did not die a month before this episode aired, he died of a heart attack in Sweden two years later.
When Morbus is sent back to the prison world with Judy and later when Don arrives he tells them that they're stuck with him there, but at the beginning of the story, he was able to send Dr. Smith back to our world easily.
At about 22 minutes, Morbus pronounces cacophony as if it is spelled cacaphony. The second syllable should sound like cough.