"I don't know if we should but we could email the bidders through ebay and warn them."

That is a suspendible offense, don't do it.

At first glance, it may seem unfair that you can't warn bidders, but it's really an excellent rule.

If we were allowed to email bidders and warn them away from an item or seller, we would see people who "thought" an item was misrepresented messing up legitmate auctions, and we'd see disgruntled bidders with an axe to grind sending all sorts of warning emails to other bidders.

eBay is a Caveat Emptor environment, and it's really up to every bidder to satisfy themselves that an item is as represented.

Emailing the seller and pointing out the error, in a non-confrontational way, is really all you can do.