I was wondering this too. I emailed Mr. Sub about ingredients and never got a response.
I don't eat at one of the Subway's here now because of an incident happening twice there (it's in a mall food court), where I explained that I was vegan and explained what veganisim was, and asked for ingredients, but they refused to show them saying "the bread is vegan, there's no meat in it" and I repeatedly ask saying "I'm talking about animal-derived ingredients, not just meat, I know there isn't meat" gets cut off with "there's no meat in the bread so it's okay", and so I say again "but that's not the only animal ingredients, there's eggs, milk ingredients, hone-" gets cut off again "it's vegan, bread never contains milk or eggs" so I reply "yes most of them do" and once again I get a "it's vegan, bread doesn't have meat or milk" and she keeps repeating this crap no matter how many times I ask to see the ingredients, so I leave and go to a different part of the food court.
I can't stand when I can't get ingredients from places. It should be the law that all ingredients HAVE to be available at resteraunts (imagine if ingredients in the future are colour-coded to say whether an ingredient is animal-derived or plant-derived, that would be awesome)
So yeah, if anyone knows what breads are vegan in Subway, and Mr. Sub, I would like to know too.