If you look at the image below, you can see the printing "bridge destroyed". In the white part of the sprue. Is this important?
There are bridge destroyed counters and a quick read of the rules did not indicate anything....
Per the Play Note under NW:IP Game Specific Rule 126.96.36.199:
To cut down on counter clutter on the map, text has been applied to the sprues between counters on the third counter sheet. Carefully cut these out and lay them along the hexside when a bridge is destroyed.
So just an alternate means of marking destroyed bridge hexsides.