On 1.0.5 I had no issues, it is only with a fresh install of 1.1 did the graphic glitches show up. I tried turning up/down anti aliasing, both fantastic and beautiful render quality, fixing directory permissions, removing the saved application state in Library, etc...
Here are some screenshots of the glitching floors, walls, and flag of the SPH (happens in the VAB as well).
To test to see if was just on my machine, I copied the KSP_osx directory from my MacBook onto an SD card and had my coworker run it on his MacBook and the glitch is not present. The differences are:
My MacBook: Mid-2014 Retina MacBook Pro with Iris Pro GPU and 16GB of memory
His MacBook: 2012 MacBook with Intel integrated GPU and 8GB of memory
I am thinking the Retina display may have something to do with it. I also tested with the low resolution option (right click the KSP executable and select "Open in Low Resolution") but got the same results.