My high school had Mickey Mouse on one of its clock faces for a long time. In the mid-80s, though, they removed it. They didn't say anything about copyright, just that it "didn't properly reflect the academic learning environment." The student body was furious and, in the middle of the night, a classmate of mine climbed up onto the clock tower (about five stories in the air!) and repainted him on there. He was still there when I graduated in '89 but he's gone now... I imagine it was a copyright issue all along. Or, eventually, became one.