I made a small track and put a dog into the minecart. As I am elsewhere in the game, some times I land on a block and I hear the dog yelp. When I return to the dog in the minecart, I fine that it had indeed taken damage or is missing and presumed dead. This has happened far enough away at times to where the chunk where that has the track is not even loaded, 300 m away. At first I thought it was a fluke and found when I took out the block it stopped but then I found a second spot.

Not related but I have a cow cooker an the cows on from time to time will phase through the cobble wall surrounding them into the next holding cell I have for sheep.