Ah, the sonic screwdriver. I almost didnt include this one because you all know what Im going to say. But I figured youd lynch me if I didnt, so here goes. Basically the sonic screwdriver has become infamous as a do-anything, get-out-of-jail-free plot device. John Nathan Turner actually banned this in the 1980s to force more creative writing out of his team. Whether it worked is debated to this day. If were being really picky, the thing should only open metal locks, probe machinery and short out sonic weaponry. And kill blue hedgehogs. No, Im joking. Basically, the sonic screwdriver shouldnt be used to just solve absolutely everything in the story. Because once you go down that route, problems start to emerge when you have to write it out. For instance, the Doctors reasoning that the sonic screwdriver would flood the radiation chamber in The End of Time begins to look questionable when you consider how easily he can sonic dangerous machines to safety in one move on other occasions.