At the part where the player has to escape from the cell, Jens says:

"(...) There is also a third option for getting out of the cell. Do you know how to do it?"
[At least this is what I hear him say]

But I can't find a way to get out of the cell other than removing the iron bar and jump out, or breaking down the wall with the hammer.

If he was referring to how to obtain the key that is inside the pipe, so that the player can open the door to escape the Cells' area, I can't find a third solution for that either. Only pushing it out with the iron bar or pouring water from the bucket.

Does anyone know what the third solution is?

...I wonder if he was just hinting on the "last resort"... You know, wait patiently in the cell for the Shadow to come and... "release" you...

The file with the audio commentary is "25_jens_multiple_solutions.ogg" if anyone wants to listen to it.

I think the third one might be to use the iron bar to break the wall.

Or wait till you die