In the scene where the Asian guy is peeing off Stiffler's balcony, he knocks over a plant and knocks out Christy. In the next shot the plant is back, and in the one after that it is gone again.
Hey, didn't you see it clearly? There are obviously two pots of plants, one at the left and the other at the right. He knocked the left pot of plant, not the right side, so I guess you had mistaken it.