Specifically, we spotted this erroneous tip inside the train car: To get from Grand Central to Madison Square Garden, take the 1, 2 or 3 train and then walk to 4 Penn Plaza. Only the 1, 2 or 3 train doesn't run through Grand Central -- it goes through Times Square. Oops!
Last night we emailed both Google and CBS Outdoor, which sells the subway ads, to see if either knew about the problem or planned to fix it. We're waiting to hear back. In the meantime, better stick to those MTA-sanctioned maps when traversing the NYC underground. They might be terribly designed but at least they're right.