When you tak the view of a hostile mob (e.g. zombie), normally, when it rotates, then your view rotates with it.
But, it doesn't! I was fiddling around in spectator mode on a new map and wanted to go on mob's view, but my point of view didn't change after at least a minute, so I went in F5 and saw that the zombie had turned his head to almost 180° i the opposite direction.

I searched for a dupe but I didn't find any, sorry if there is actually a duplicate of this one.

Thanks,
Giorgio