People keep listing the plot holes they spotted in the episode. I'm not sure it had more than usual, but they were obviously more visible for some reason.

Structurally I understand the trick the companion thing - because they couldn't let Clara live 300 years so thematically I don't think it was as significant as what the Doctor did to Rose. Of course, that's taking a step away from the action. It was obviously the same from Clara's point of view.