What an interesting question. I found the following:
http://www.geocities.com/Hollywood/H...96/oz-lore.htm
"Most folks believe that 'the red brick road' is an L. Frank Baum book convention that made it into MGM's 1939 classic film. In his books, the Land of Oz was divided into four quadrants and each was designated a particular color: Winkie Country = Yellow, Gillikin Country = Purple, Munchkin Country = Blue, and Quadling Country = Red. Glinda the Good was the ruler of the Quadlings in L. Frank Baum's Oz series. As her bubble floats away from Munchkinland in the 1939 film, it appears to be following the red brick road. Therefore, the red brick road most likely leads back to her homeland, Quadling Country."
Also on a website about ditched song lyrics:
http://www.geocities.com/SoHo/Cafe/5536/wizardoz.html
"No one knows why this was written and obviously it didn't work into the story. At this point so many new songwriters were being hired and fired that none were given time to read the script before writing.
Follow the red brick road
Follow the red brick road
Follow follow follow follow follow the red brick road
The writer of this song, just newly hired, unknowingly wrote of the "red brick" road which can also be seen on the ground at the beginning of the "yellow brick road" swirl. As Dorothy tried to follow it though, she found herself heading back to Town Square. The Munchkins seeing her return then began singing the entire scene over. The director and his crew of 75 were unable to stop them for 45 min and the writer not only ended up losing his pay, he actually owed the production company $4500 in lost cost time, of which between the years 1939 and 1945, just before his untimely death, he had only paid back $3245.23."
Of course, the most fun is playing the video with Pink Floyd's Dark Side of the Moon. If you've never experienced this, you gotta try it. Here is a web site that explains how to set it up:
http://www.pinkfloydonline.com/synchronizations.html