I'm rewatching some scenes and the ending of the police station part in part 17 is interesting. The clock on the wall is stuck at 2.53. the same time that the evolution of the arm mentions in episode 2, the time where Mr. C and Cooper were supposed to switch places. "253, time and time again, Bob... Bob.. Bob...".
A little bit before that, the arm says that the doppelgänger has to go back in before Cooper can go out. Mr. C ruined that plan, but isn't it weird that Cooper was able to return in episode 16 even though Mr.C is still hasn't gone back in? Maybe "before you can go out" isn't returning to that world, but waking up somehow. There's Cooper's face superimposed, he is observing what is going on, says "we live in a dream" and everything turns black.