In multiple recent games, I have noticed that I can sometimes "see" a card in my opponent's hand that was never actually revealed, I believe always following their casting torment of gollum on me, because the card appearing in their hand is always one that was in my hand. I have confirmed that the card never existed as later game actions such as me actually being able to see their hand demonstrates the card was never actually there, and my 17lands.com game history shows there was never any time their hand was revealed