There's a Collector Card box in the back of the garage in Subway Town. http://i.imgur.com/EEhcA.jpg
Any idea how to get it?

According to the guide i'm following for card locations, there is only one card in Subway Town:

Authority Mutant - Located in the Resistance Base, next to the dead mutant within Elizabeth's tab.

Yeah I couldn't find any mention of that card on the internet, but you can clearly see in game that it's there!

I think it's there to frustrate you. Within view, but out of reach. Taunting you.

If it aint flashing you cant collect it..... lol.

This is not in the xbox version as a flashing collectable.