Switching from survival while inside mob doesn't kick you out

If you go to spectator mode and spectate an enemy mob, then switch back to survival, you remain in the mob. Your health bar appears to be that of the enemy, and they will immediately attack you as if you were standing right on top of them. For example, a creeper will immediately explode.

Further, after respawning from this state, you will retain the altered vision from the mob you were spectating.