I love this list, but there was one that seemed odd.
"Time passes at the same speed on top of a mountain and at the bottom of a valley"
Unless you're writing software used to track very intense scientific measurements requiring information about time down to the sub-nanosecond, I don't see how the effects of time dilation between a mountain and valley would ever have an effect on program logic.
Everything else about time can and will bite you at one time or another.
"Time passes at the same speed on top of a mountain and at the bottom of a valley"
Unless you're writing software used to track very intense scientific measurements requiring information about time down to the sub-nanosecond, I don't see how the effects of time dilation between a mountain and valley would ever have an effect on program logic.
Everything else about time can and will bite you at one time or another.