I remember having dreams whose contents were physically impossible, to the point that when I thought about them afterwards, I couldn't reconcile them with reality in a meaningful way, although when I dreamed them, they seemed to be logical and coherent with reality. The only example I can recall: I was climbing a set of stairs, and there was a large gap in the middle where there were no stairs, and logically I shouldn't have been able to cross from the bottom step to the top, and yet I did. When I think about it afterwards, I can only visualise this as some sort of cheap visual effect, by either teleporting between the two steps, or unnaturally distorting my limbs; but I remember that while dreaming, there was no such effect. It just worked.
How is it that I could dream something that is completely incoherent with reality, or completely impossible, that I can't fully reproduce in my head while awake?