Continuity mistake: When Brenda takes a drink from her glass, there is over half the glass left as she holds it in front of her and savours it. The movie then cuts to a wider shot, and there is maybe 25 percent left in the glass. (00:28:30)
Factual error: When McCleod jumps into the ocean, his kilt catches the wind. We then see that he is wearing an undergarment. Scottish men don't wear undergarments under their kilts. (00:48:15)
Answer: What the punishment is isn't shown in this movie, but since even the Kurgan follows it, it must be high. In Highlander 3 we see that fighting on holy ground at least destroys the weapons they are fighting with (although only Macleod's for some reason), it's possible the ultimate penalty is given when an immortal kills another immortal on holy ground. A good guess is the penalty is death.
lionhead