Matt Damon was strung up by his waist for the torture chamber scene, but he could only stay up there for 90 seconds at a time because the rope was crushed his ribs, cutting off his air supply.
When Will cracks the magic mirror, it causes no ill effect on the queen, and apparently repairs itself, since the crack is not visible in later shots. However, Jakob later chops up the mirror, which does not repair itself and causes the queen to crack apart accordingly.
At the beginning of the movie, Will rides a gray Andalusian. When he and Jacob ride into the forest with the trapper, Will rides a fat gray mule. Jacob is on the same horse, with no explanation of why Will changed horses.