Red Flags for DMs?

[Quertus]

Not really. The default assumption is, that as long as nothing says otherwise, in-game physics are the same as our real world physics. Ex abilities point out were that assumption is not true and in-game physics differ from real world physics.

I think an (Ex) shadow jump is actually a good example for this. We know that it is not physically possible to enter a shadow. But we also don´t have coterminous planes, so we don´t know the physical relationships here. This (Ex) ability tells us, that there actually is a physical relationship here, that someone with the right training can actually put to use.

Oh, well, that's different, then. Of course you can jump through a shadow if it's a gateway to a coterminous plane. That's not breaking physics, that's using the physics of the world.

Just like mages do when they cast spells.

Rats. I'm back to being confused again.