Re: Easily fixed...
For the mouse button scenario, I think what happens is that right handers will tend to replace the word "right" with "the one you use automatically", and "left" with "the other one".
The basic problem is that the primary mouse button is (by default) on the left instead of the right. And that many - if not most - people don't have the concepts of "left" and "right" hardwired into the way they think about their bodies.
(If it's of significance, I'm right handed, but usually use my mouse with the left hand, with the buttons in their default configuration.)