Have they or will they explain how Scott remains aboard the Enterprise? In the last film, he was assigned to an outpost and then beamed aboard the Enterprise illegally. Now he's the Chief Engineer? The same holds true for McCoy. He was assigned to the ship but only took over as Chief Med Officer after his superior was killed. Is it automatic that he would just stay with the Enterprise? Or would a Star Fleet member with more seniority be up for the job?
Or am I just being nitpicky?