In the opening fight scene, it may appear as if Josh Michael Burton blocks a "low blow," but this is actually an optical illusion. The punch was actually aimed at Josh's stomach, and the director never even intended it to look like a low blow.
Real swords were used in some of the opening fight sequences. When using real swords, the action was shot in slow motion, and then edited at various rates of speed.
Invisible string and duct tape were used for some of the, deliberately, low budget effects shots, such as the effect where the mask attached itself to Josh's face.