Aversion: the heavyset man in the audience during "Denton, Denton USA" is not John Candy despite looking just like him.
Old Shame: Slight subversion. While Richard O'Brien dislikes this film due to it's confusing plot as a result of its many rewrites, he does praise the music and the fact it foretold reality TV by two decades.
The Other Darrin: Of the four returning characters from Rocky Horror (Brad, Janet, Betty, and Ralph), only Ralph is played by his original actor.
Once it was clear that Rocky Horror Shows His Heels wasn't going to go forward, this project was originally conceived as The Brad & Janet Show and was to be filmed on-location in Denton, Texas. Many of the songs that were written for Shows His Heels were re-purposed for this one note (for example, what became "Looking for Trade" was about literally looking for the "young blood" necessary to revive Frank-N-Furter). However, the 1980 SAG strike and other circumstances forced them to shoot entirely indoors in London, and rewrite the script to match.
When it comes to actors, Tim Curry was worried he couldn't pull off the required accents for Brad and Farley, Susan Sarandon (Janet) wanted a prohibitively-large amount of money to reprise her role, and Barry Bostwick (Brad) was unavailable. (Cliff DeYoung was the one they originally wanted to play Brad Majors in RHPS.)