In the new 1.11 snapshot (16w32a). When spawning in a Horse/Mule from a Spawn Egg, then trying to ride it by right-clicking crashes the game. For me at least Right-clicking on Donkeys, Skeleton and Zombie Horses does not crash the game. But the other people on my server crashed due to right-clicking on these animals.
MC-105956
Trying to ride donkey/mule from spawn egg crashes the game
Resolved
Fixed
1
Can confirm for donkey and mule; cannot reproduce for regular horses, zombie horses, and skeleton horses.