The guest food thing is pretty uncommon. I can play for hours without getting it, but then one comes out of the blue and becomes an ongoing issue.
I am mystified by the whole security guard dynamic. I hire them, and they at low efficiency, spending most of their time sitting around in the break rooms, but I still get vandalism and so on. Security cameras don't seem to make much difference, nor does adding restrooms and food and so on to make guests happier. I always seem to have about 10% of needy guests in the heat map, no matter what, but most are pretty happy.
I've run across another weird bug from time to time, and it drives me kind of bonkers. I get an alert for a particular habitat: "Keeper (or mechanic) can't reach habitat due to work zone set up" as if the gate isn't connected to the path or no one is assigned. However, in these cases the habitat is most definitely connected to the path, as are the keeper hut and workshop in their work zone. In fact, it seems to happen most often when the buildings are really close to the gate. The appropriate workers are assigned, and sometimes there's even just one enclosure in the whole zone. The workers actually do visit the habitat just fine, and the message goes away on its own after a while. Deleting barrier and redoing doesn't help the way it sometimes does with stuck staff.
I've reported it on the issue tracker for a zoo where this was happening constantly with a particular habitat, and I even sent my saved file, but we never figured out why it happens. Trashing and rebuilding the habitat from the ground up on the same plan didn't help either. So it appears to be related to a particular geometry with the path, buildings, and habitat gate where the workers can path, but for some reason the game thinks they can't.
It's not exactly game breaking, but it bugs me to have an alert up I can't do anything about, even if it isn't really an issue.