In Mark 15:38 it says that the Temple curtain was torn in two from top to bottom. Is there any historical evidence that this actually happened: Either in some Jewish texts or some other credible writing outside of the New Testament?
As far as I know there is not other written source confirming this particular event other than the gospels. It is highly doubtful that any Jews would have reported this incident (other than those who converted to Christianity, of whom there were many). It would have been an embarrassment. In fact, we have relatively few Jewish writers from this time who reported day-to-day events, so the likelihood of this particular event showing up in another extant writing would be quite remote.
Of course, there will be skeptics of Christianity who will try to use the fact that this is not reported elsewhere as evidence that this did not happen. This is the weakest possible evidence against the reliability of a gospel account. Unless there is evidence or reason to believe that Mark is lying or is reporting a lie in his gospel, we ought to make the most reasonable assumption that he is reporting historical fact. Mark wrote his gospel in the 50s AD (or perhaps the 40s or 60s, depending on whose opinion you listen to). This was only about 20 years after the event. The fact that there were thousands of eye-witnesses to the events surrounding the crucifixion and that Mark’s account was written when most of these eye-witnesses were still alive to refute any obvious errors is a strong check against false reports, making the believability of what Mark reported even stronger. For these reasons, I believe that the most reasonable conclusion is that the curtain was indeed torn at the time of the death of Jesus.