When you place a minecart on top of a slanted un-powered rail, it just floats there as if nothing happens, but fixes itself if powered or moved. However, if you drop another minecart of not of the floating one, visually it slants the other way but the hitbox is in the same place as as the other one.

AND THEEENNN, if you continue to drop minecarts onto the same spot, and then break a specific block, they all fall into the same block, which is not supposed to happen, even though I really want Mojang to keep it in.

Watch the attached video to recreate.