From what I've found, there were something like 150 contingency orders so as to hide what Order 66 was meant to do.
The first time I saw "Return of the Sith", I thought he gave the order "666", and I thought, cute, the devil.
But then I learnt it was "66". Is that still referencing the devil? Is it just a number pulled from a hat?
George Lucas also did "American Graffiti" which references Route 66, but I don't how to connect that with killing Jedi. Jedi road kill?