On May 18, 1980, I was visiting some friends of mine in southwestern Washington State when Mt. St. Helens erupted. At the time of the eruption, I was walking down a Forest Service road. I saw the entire northwest side of the mountain just kind of slide off, followed by an enormous explosion.
Now, as it turned out, it was the northeast side of the mountain that collapsed. I would have sworn in court that it was the northwest side. I spent many, many hours of my youth on those Forest Service roads, and I knew exactly where I was in relation to the mountain. Still and all, I was simply... wait for it... mistaken.
What can we conclude from this little story? Eyewitnesses, even to dramatic events, are not infallible and should not be treated as such.