In games with more than one player, when you reveal normally hidden areas (such as your hand) to just a few players, but not all, the game reveals them to all sometimes, but even if this doesn't happen, the game log in the bottom of the screen shows explicitly what card that player drew to all of the players (i.e. X just drew a Swamp) even when not all the players are supposed to know.
Some other times, again in multiplayer, revealing a hidden area to one specific player via right click -> reveal to -> Player X -> all does not work. The message shows, but the area is still hidden (i.e. you can only see the back of the cards).