Continuity mistake: During the final fight between Jean-Claude and the bad guy, they are both holding onto a shotgun. Initially the barrel of the gun is in J-C's left hand. But without either of them letting go of the gun, suddenly the gun switches end-for-end and the stock of the gun is in J-C's left hand. It looks like they probably re-filmed the last of the fight so the bad guy could use his right hand to hit J-C with the butt-end of the gun.
Revealing mistake: Toward the end of the movie when Van Damme is on the motorcycle watch the pull back shots. You can see the stuntman in place of Van Damme. In addition, the stuntman is clean shaven in some shots where Van Damme looks like his beard is growing in. It's very noticeable, especially when he goes down the mountain. You can even see the ramp set up as he first goes down.