Power of the Triforce

[Kitsu]

And according to the laws of physics, the sheathe isn't supposed to point up the middle all the way...

That's not what he meant. He's saying that the sheathe is for a katana. But Link isn't holding a katana...

As for the pants, he might be referring to how it's somewhat hard to tell the pants apart from his shinguards because of the colors.

For the looking down part, it is kinda hard to tell which way his eye is looking. I didn't think he was looking down when I saw it, but I can see how one can come to that conclusion.