800.4a. When a player leaves the game, all objects (see rule 109) owned by that player leave the game, all spells and abilities controlled by that player on the stack cease to exist, and any effects which give that player control of any objects or players end. Then, if there are any objects still controlled by that player, those objects are exiled. This is not a state-based action. It happens as soon as the player leaves the game. If the player who left the game had priority at the time he or she left, priority passes to the next player in turn order who’s still in the game.
Obviously, this is an issue that needs to be fixed. The easiest fix (proposed by TranscientMaster) would be to end control-changing effects first, then make everything else cease to exist. His other potential solution was to make everything on the stack that player owns cease to exist instead.