Continuity mistake: When Natasha is shot by the robot, the shot travels right through her, like a normal bullet would. Yet in every other scene when the robots use their pulse cannons, including when Rasheed dies, the shot always causes an explosion. With Natasha, no explosion was seen or heard.
Plot hole: When the first sterilisation unit encounters Nicholas in the desert, he commands it to 'cease operation' and it becomes harmless. There was no reason why he couldn't have used the same command later on in the movie when he encountered deadly robots, particularly when one was teleported to the lab.