The simple way for the Earth to rotate clockwise instead of counterclockwise is not for it to stop rotating in one direction and commence rotating the other way, it is for the planet to physically "flip over," without ceasing to rotate at all, though the period of rotation might be strongly affected in the process.

Something has happened to cause Venus to rotate "upside down" and Uranus to rotate on its side (also retrograde); possibly what happened was the interaction of the planet with another gravitational field -- possibly a passing planetary body, something like the "passing star" that was once posited to explain the presence of planets at all.

What kind of physical consequences would such a flip have as it was happening and after it was complete?

{Note: this is my first post at this deluxe new site for HZ. I don't think I will live long enough to check out all the bells and whistles, but just for the record I would like to restate what everyone already knows: Robert Shepherd is a creative genius. Kudos. But I have no clue where this post will wind up...}