AH the scar polemic again!!! Tha scar is havong people talk!!!
here is what I've read on the subject. In the first season, we saw Jack with multiple scars. ( c.f. picture above) For some reason, RDA's characters always get hurt on that particular eyebrow ( MacGyver did a lot too) . BUT the scars we saw in season 1 were not permanent. THE scar we all love appeared at the end of season 2. For some reason, they ( they being THEY, you know... the ones who make all the decesions...) decided to keep it. The scar is "made" by the make up artists. It is not one od RDA's scar ( I'M sure he has some of his own with his tendancy to love extrem sports !!!)
I hope that answers you question. I don'T rmember what particular episode it appeared though.