Play a Der Riese split screen game. When Player 1 teleports, the screen calobration changes.

Compare your screen to Player 2's screen in the same rooms and you will see that Player 1's screen is darker/different. This does not happen to Player 2 when he teleports.

I don't know if any other conditions affect this, but I don't think so, it seems to just happen whenever Player 1 teleports.

Because of this, I almost never teleport (in split screen games) as it is more difficult to see.