So I have a friend who owns this game and brought it over last night for us to try. Great game and the only question that came up that we did not have a "locked down" answer on involved the old world card that had Orcs in three regions causing each player to only roll one battle die. When the first die rolled in one of these regions came up a 6 we were confused. In reading the rules very closely we decided it counted as a hit, but no further dice were rolled for the explosion as they would be additional Battle Dice (prohibited by the Old World Card).

Were we correct? Has anyone else encountered this situation?

An explosion is a hit and then re-roll. It's not an extra die so it technically is no more than one die. You should hve rerolled it to see if you got additional hits.

The point of the OW card is just to roll a maximum of one die, but if it explodes, roll it again.

seconded - this is how I'd interpret

Agreed. You are only able to roll one battle dice, but if it explodes, you get to reroll it for more hits. Explosions chain too so if you consistently roll 6 on the same die...you pretty much own that region (=