I think that if you focus on your character's reactions to things not being where they thought they left them, then it will clue your readers in that you're being sloppy but are being cagey.
Especially, if sometimes your narrative has the character take a specific action -- puts the dog outside -- then finds it in the clothes dryer. A silly and extreme example only offered for the sake of this discussion.
But, with the narrative showing the dog let out into the backyard, then the reader and the character will experience the same "what is going on here? And why is my dog so snuggly soft. Dryer sheets for dogs! Call the patent office."
By intermixing narrative showing some of the mysterious reality-warping events happening within the character's POV -- the coffee cup on the desk -- then later showing the character's reaction to the coffee cup somewhere else, I think you'll provide enough of a clue to your readers that this is a thing and not evidence of poor continuity on behalf of the reader.