('os.name') == 'Mac OS X'
('os.version') == '10.9.5'
('os.arch') == 'x86_64'
('java.version') == '1.6.0_65'
('java.vendor') == 'Apple Inc.'
('sun.arch.data.model') == '64'
In Creative mode, at night, I used "/time set day" in an area where zombies and skeletons were already out. Some of the mobs caught fire, but some just stood still. The mobs, including zombies, skeletons, creepers, and an Enderman. didn't make sound, and didn't target me in survival mode.
When I exited the world and reloaded it, the mobs were gone.