Isn't it because they were probably put among each other or even other objects in one container, shaking around in it and bashing into the container and each other? The sloshy fluids in them would make the movement more unpredictable too I imagine. Meanwhile, he's the actual target of this spell and didn't seem to be particularly jostled around when it was just him and his bike. Perhaps the spell got more violent about it towards the edges of the area of effect created by the carpet. A lot of stuff we don't know here, including "how knowledgeable the author is about physics and how much of that was thrown out the window for 'it's magic.'"I don't know what bottles they use for sake and the like, but if it's like a wine bottle shouldn't he have broken bones if the shock of transfer could break them?