Took the backwards train

I was in the subway station and supposed to go to stop C.

Stops:

A B C

I got on the train at stop B and I took the train to A. My friend asked why I was late, I said:

I took the backwards train to A.

Is the sentence natural?

No. Try again.

I took the wrong train which went in the opposite direction (from my destination).
I took the wrong train which brought me further away from my destination.

It's probably not necessary to elaborate, and Rover's suggestion of simply 'wrong train' is adequate. Wrong is wrong, no matter which direction you wrongly went. However, if you really feel the need to specify which train you took, then If you know the general direction the line runs, you could refer to it as the '(whichever direction applies)bound train'.

Ah, I took the eastbound train instead of the westbound.

Sometimes they're also called uptown/downtown lines, or X train where X refers to a particular district, region, or part of a city.

I accidentally got on the Dongcheng train instead of the Xicheng train.

Surely there's some kind of numbering or labeling system. If so, then state the name of the line you took.

I took the O line instead of the P line.
I accidentally grabbed the 127 instead of the 429.

I think it's OP's intention to elaborate about how he took the wrong train. Is there anything wrong with my versions?