Mario Kart 64 is when the Fake Item Box is at its best, as it is way better than all of its later appearances. Firstly, the Fake Item Box in Mario Kart 64 is actually convincing because you can barely tell it isn't the real thing. Second, unlike in all of its later appearances, it can be used for defense and can float in midair.

If the Fake Item Box were to ever return, I would make it actually convincing and nearly indistinguishable from the real thing like in Mario Kart 64, and I would completely change its function so that instead of acting like a Banana, it flies to the nearest Item Box group and infects a real Item Box. Upon hitting the item, the player will flip over and have their item stolen, giving said item to the user. Only one Fake Item Box will be able to be in play at a time, as once a Fake Item Box is in play, another Fake Item Box won't be obtainable until the current one disappears, either over time or when someone runs into it. From a distance, the Fake Item Box will have a normal question mark, only on approaching will the question mark turn upside-down. This is a rework of the optical illusion from Mario Kart: Double Dash and Mario Kart Wii, where the Fake Item Box changes color depending on the distance from the item.

Pretty smart of Nintendo to modify the Shell model and add spikes on it. the yellow spikes on the Blue Shell make it look so intimidating in this game.

P.S: They also removed the shell cracks, pretty neat