To make:
Build an uphill track, include some power or detector rails.
Place a minecart on the slope, over either of those types of rails, when they're in the powered state.
It glitches through. When it reaches flat ground, it's sunken into the ground, still attached to the track.
Note; the rails with the problem have very low hitboxes. Not sure if that's at all related.
(this is not the minecart-sinking-into-the-ground-when-derails bug; it started happening with the new minecart physics.)
They reverted the physics, so this is gone in 17a.