In the first season the veteran and mechanical engineer Vladmir Beck experimented with building mines. He and other "Colonists" had plenty of ideas regarding defense, which eventually went beyond their machetes, maces and axes to a working flame thrower and taser.

The problem is that these defense measures were put on the back burner initially so that they could focus on food and a clean water supply. Not to mention that the colonists were initially forced to stay awake and went through constant physical activity before the show even started as part of the simulation.

In any case, the creators, producers and writers of the show get to watch you 24/7. No matter how masterful your plans or what you build for defenses, their ever-presence will be translated into intel for the bad guys. They also have the luxury of knowing the set far better than the players ever will so there will be ways around your defenses no matter what you do. They also have the ability to "script in" things to make your precautions backfire on you.

With all the talk on the web during and after the first season, I would expect there to be a security and defense specialist this season.