Why was Porridge emperor of the galaxy again? That would have made a cool twist if it had been employed in the middle of the episode; while the Doctor is playing chess, have Porridge warp himself and Clara to safety, and have Clara appeal to his bored, exhausted side to be the hero his duty won't allow him to be, rather than nuking the planet.
Should have been a two-parter. I love Mr Clever, but the Doctor's internal battle shouldn't have been the crux of the entire episode. Hell, exploring the emperor's desire to hand off his responsibilities to someone else could have been a cool concept if it was actually in the plot itself, rather than a weird epilogue.