I noticed that there are 2 bugs when playing with 2 or more players,
1 - Certain effects that were supposed to affect player 1 end up affecting player 2 because he is the first player in the round. Unfortunately I don't have an example to give now, maybe later I'll get an example when I'm playing with some friends.
2 - There are cards that the player has to be in alter-ego to resolve can be resolved by anyone, For example 21029 (Sap Power) which could only be resolved by the one who is with it, can be resolved by anyone in alter-ego.