One of the ways we can tell that reality has shifting is to
notice that something has transported from one place to another without any
apparent physical cause for it's movement.
Here are some examples of transportations I've witnessed:
Child's Spill-Proof Cup
My daughter had lost her cup somewhere, and we looked everywhere... finally
discovering it in a place we know that neither of us put it.
My daughter's favorite shoes once vanished for several days... before
appearing on top of her bed (a place we never put them)!
I once purchased a magazine exactly like the one my friend had at her
house... in fact, the day I bought it from a store that had no other
magazines by that title, her magazine vanished from her house.