I've thought of the teleporting to the other side of the planet and being upside down thing also.  Didn't think of the different speeds at different latitudes though.    Another interesting thing:  If you could teleport but not control momentum, you could still jump out of a plane without a parachute.  Jump out of the plane on one side of the planet, fall until you have reached terminal velocity.  Then teleport to the other side of the planet and you'd then be "flying"  up into the sky.  (really, falling though).    Fly/fall up until you slow down to at most 10-13mph.  All the while making sure that you never change your body/head orientation. Then teleport back to the side of the planet you jumped out of the plane from about max 10 feet from the ground.  Your feet will still be closer to the ground, and land on your feet at the same ideal speed as you'd land from sky diving.