When a mob walks around aimlessly, it does this by choosing a random nearby location to walk to, then walks towards it until it gets there. If that mob is moved before it reaches its destination, it will continue to try to get there, even if that location is in an unloaded chunk. This occurs with teleport commands, riding mountable mobs, water streams, and any other way of moving them.
A related problem occurs with passive mobs and their "panic running" when they take damage. The panic run does not use this method, so a mob interrupted during their panic will finish their panic running and then stop normally. If however, they were already moving when they took damage, then this bug will occur and they will continue to move at increased speed until they get back to their original destination.
Related issues
Comments
Sonicwave
kumasasa
Is this still an issue in the current Minecraft Snapshot 15w49b or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
migrated
Confirmed in 16w15b. This bug is the cause of MC-19413.
wobst.michael
Is this still an issue in the most recent versions (currently that is 1.10.2, or 16w43a) of Minecraft? If so, please update the affected versions and help us keeping this ticket updated from time to time. If you are the owner/reporter of this ticket, you can modify the affected version(s) yourself.
Confirmed, it occurs also if you push them or move them by other means.