Dreams.

When replaying a dream, the brain adds details that weren't actually there. After replaying it again, it might even become a completely "different" dream. It's a strange phenomenon, much like how dreams are often quickly forgotten upon waking.

This happens, but I personally try to avoid it. That is, I retain some attempts to explain the scene I saw, but I exclude unnecessary details. This should be evident in how I describe my dreams. No, I can't guarantee 100% accuracy, but I try to keep it as concise as possible.