Like in previous updates where this was an issue, mobs (specifically passive mobs) are able to glitch into solid blocks upon (re)loading chunks in which they are located. This was not an issue at all in every previous version of the last major update (1.8.x). The first screenshot provided is of rabbit meat on the ground when I had not killed a single rabbit only after immediately loading my world. The second screenshot is of an escaped (not wild) rabbit that occurred at the same time the events in the previous screenshot occurred.