Good Question...

On...any eyewitnesses to refute the NT?

You claim that one of the reasons the NT Scriptures are reliable is because there were too many eyewitnesses around that would have criticized and brought to light any inaccuracies. I was curious as to how they would find out about them. Did the disciples publish the NT texts?

'Publishing' did not exist in the same sense that it did in the larger Roman cities, in which a special class of slaves existed to make copies of manuscripts, but there WERE literary forms used quite often for this purpose, and that was the 'open letter' to the nobility...Luke appears to be such a treatise, made for general consumption, but addressed to an upper class citizen Theophilus...

The first round of documents were the letters of Paul to the churches, from 40-55ad...these circulated widely, and were available to anyone who could make copies...

The gospels were probably written up in the 50-60ad time frame (except John) and they somehow appear everywhere at once! (even John, written at Ephesus, shows up in North Africa within a couple of years!)...

These works were available to outsiders as we know from a couple of things:

1. The Gnostic 'outsiders' (as well as 'insiders') wrote about them often (see the Bias debates)
2. The first Christian apologists (100-150 ad) appealed to still-living witnesses of these things (e.g. Quadratus) and to fulfilled prophecy (e.g. Diognetus)...and DEPENDED on external access to this...
3. The first anti-Christian apologists (e.g. Celsus, 170ad writes) are VERY familiar with the NT writings...

All the data we have says that it was available early...

Also, you have to remember that these Christian communities before 90ad were parts of Judaism, and so, just as scribal documents would be copied and available from ELDERS, so too these early Christian dox would have fallen into that pattern...

were they widely available?

I think I just commented on that above...briefly

Isn't it likely that the actual eyewitnesses never really saw the NT texts at all, and therefore didn't have any chance to challenge them (assuming there were inaccuracies at all)??

actually, most of them probably would...

if the dox WERE in finished form within 20 years of the Cross (and in oral and partial-written forms much earlier), and if they were developed within the Judaistic-synagogue environment (such as Acts described) then the people (especially the leadership which always followed Jesus around) would have had EASY access to it...remember Peter and Co. taught DAILY in the temple about these things at first...

also, a great number of priests had become Christians early on, and would have been interested in the written forms as well...

sorry this is so brief, and so late...but I really do plan to write a major piece on this issue...I think its a VERY GOOD question...and thanks for asking it...

more later...glenn