This story is so great that I had to link to it. Go read it now.
Stay on Target: Real Life Tron on an Apple IIgs.
As soon as they started explaining how missiles were added to the game, I knew where this was going. I didn't expect the result to be so entertaining and interesting. It's certainly a spectacular bug.
It also reminded me of my early programming days in high school when I learned that you could crash Windows 95 by doing something similar to this.
I remember being disappointed when this didn't work in Windows 98.