In some games, cards can display a pink box with a pink circle superimposed. These cards require the player to control a bunny in the Bunny Circle at all times while the card is saved. If at any point the player has no bunnies, the saved card is immediately discarded.
In KinderBunnies: Their First Adventure!, the pink box is replaced by a pink star that functions in the same way.
In addition to the pink box, cards in Ultimate Odyssey and Heroes vs. Villains can also have a green rectangular box. If the green rectangle is lit, the card may be played only if the player controls a city in the City Circle. Similarly, cards with an orange or black rectangle can only be played if the player has a Psychic Penguin or alien down, respectively.