UPDATE: The error is repeated in The New Republic. ("The veterans featured in the organization's TV ad claim to have 'served with Kerry,' but none actually served on the same boat.") The "same boat" claim is dumb -- but forget Clintonian parsing of what "served with" means, it's also not true. I thought weeklies were supposed to have the time to get stuff like this right.
ANOTHER UPDATE: Refuting this error is this new ad from the Swiftboat Vets featuring Steve Gardner who says that he spent more time on Kerry's boat than any other veteran, and that the Christmas in Cambodia story is false. It's going to be hard for the Kerry campaign to argue with that, since they've already admitted it.