Executive Meddling: The only way to describe how Steve Jobs muscled his way into the project over Jef Raskin's objections. Which might be a good thing, really, as the tension in the group already started to mount at the time.
What Could Have Been: Entire books could be and have been written about ideas on which Apple didn't follow through — the Taligent and Copland operating systems, the Jaguar platform (eventually replaced by the Power Mac), the Integrated Burrell Machine, the Macintosh Office, MacBasic, G5 PowerBooks, Cell Macs, and several possible mergers that never happened.
In 2001, Apple approached Sony because its Vaio notebook line was appealing enough that they were willing to allow Sony to make Mac clones. They even had OS X running on a Vaio laptop (note, this was before the official transition to Intel). Sony declined, on the grounds they didn't want to pull resources away for supporting two OSes when they were busy working on getting Windows optimized.
Mister Macintosh, an Easter Egg that would appear at random when the menus were invoked. It was halfway implemented then abandoned. It's legacy could be seen in the Kid Pix software, which drew icons in the menus.