digital pocket watch hurrr...

So... when you miss your train stop, the best thing to do it get off at the next stop with a middle platform so you can catch a train going the opposite direction without having to pay another fair.

In NYC it's mostly just express stops that let you do that. In the very large ones, like Times Square, you have to go up a flight of stairs to get to the opposite platform but it's set up so you won't have to pay again. Just remember to check which stops are what if you're ever using a subway system so you don't get lost!