Continuity mistake: In most of the scenes it is quite evident that Jessica has only a thin green dress on; when she meets Box she takes it off and she is nude. Later when she is outside of the dome and walking through the woods, she ducks to avoid some brush and she now has underwear on.
Revealing mistake: During the scene when David is fighting off the large beast in the arena, there is a shot where you are looking right down its throat. Inside the "creature" you can see a light emanating from inside the mouth of the suit, probably so the actor inside could see while acting in it.