Continuity mistake: When Eddie escapes the deep freeze, he wears three rings on his left hand (his middle and ring fingers and his pinky). Bizarrely, the pinky ring actually disappears in quite a few shots, including when Eddie plays the sax and when he lifts Columbia, just before they mess around on the floor.
Factual error: The criminologist describes the events of the movie as taking place "on a late November evening". In the very next scene, Brad and Janet are driving in Brad's car, and President Richard Nixon's resignation speech is playing on the radio. Nixon resigned in August of 1974.
Revealing mistake: When Riff Raff and Magenta burst in after Frank's song, Janet steps away from Frank's side into Brad's arms. Watch Brad's face - you can clearly see the look of pain, as Janet steps on his foot in four inch spike heels.
Revealing mistake: When Dr. Scott is being pulled through the castle by the Triple Contact Electro-Magnet, you can see the cable and the cut in the carpet, that the cable runs under, pulling his wheelchair at the top of one of the staircases.
Revealing mistake: Just minutes after Rocky's creation, when he is lifted out of the tank, there is a nice close-up of Rocky's face. The newly created man with the "Charles Atlas seal of approval" has a few silver fillings in his upper right teeth, which are easily visible as he sings, "Over my head and I've got the feeling..."
Continuity mistake: After Frank-N-Furter makes his initial appearance, when he bumps into Janet on the way out, her necklace chain is under her large pink dress collar. Once Frank-N-Furter leaves, her chain is actually around her neck now, over the large collar, so Riff Raff can easily pull the dress down unhindered.
Continuity mistake: After Frank kisses Janet's hand, as she puts it back by her side you can see his lipstick on it. When she reaches out to take the shirt from Brad, Frank's lipstick mark is gone.
Audio problem: During "I Can Make You A Man," when Frank slides his finger down Rocky's chest while saying "ste-he-he-he-heam," you can hear a solitary beep from out of nowhere, from when the synthesizer was hit accidentally during that part of the song and was never edited out (it is on the CD too).
Continuity mistake: In the dinner scene, Riff Raff pours Dr. Scott's wine in one shot and again two shots later.