What is the significance of Mona Lisa in the Rocky Horror Picture Show? The painting shows up everywhere - it is there during time warp and also in the final scenes.
Apparently it's simply intended to show that Frank, while cultured, has a very twisted appreciation of art. According to the film's production designer Brian Thompson their thinking was that Frank loved the Mona Lisa so much that he got a bunch of copies of it and shoved them all over his house, not really caring that they were low quality repros.
“I imagined that Frank [N. Furter] had an insight into art he had seen, maybe in books or movies or somewhere and decided he wanted.” For a moment Thomson becomes Frank soliciting the Mona Lisa from the Louvre: “maybe a picture of that woman. We’ll have two of those.”
“To Frank it wouldn’t matter if they are black and white Xeroxes facing opposite ways. I may still have all the letters that I wrote from Frank to the Louvre and places. There are also letters between Frank and the local authorities regarding noisy motorcycles and a strange blue glow coming from his house. They’re never seen in the film but everything was totally authentic.”
Frank seems to appreciate great works of art.
This is one of many references to famous works of art in Rocky Horror Picture Show. Others include:
The Creation of Adam by Michelangelo
Arrangement in Grey and Black No .1 (aka "Whistler's Mother") by James Whistler - this is actually a photo recreation of the painting, and Meatloaf is posing as Whistler's mom
American Gothic by Grant Wood
Two copies of Michelangelo's David
The Kiss by Auguste Rodin
The Last Supper by Leonardo Da Vinci