OK, so I may have re-watched the episode and liked it better second time round 
The bits in Clara's dialogue I found jarring were:
- The opposite of bliss is.... Carlisle (rather than despair or sorrow)
- It sticks out like a.... big chin (rather than a sore thumb)
Big chin was mentioned in the Dalek ep, wasn't it? So that may be a hark back to that episode and Carlisle may be a clue to a future ep?
Two other things I noticed during the re-watch. Near the start, Emma says "She's dead". We're supposed to assume that she's talking about the spirit, but the spirit isn't dead - it's just in a parallel universe. Next thing, Clara pops up. What if that was supposed to refer to Clara? The undead presence Emma detects is Clara. Emma later says that as an empath she sometimes projects what she wants to see/feel from others - what if she can only believe her eyes that Clara is a living, breathing human girl right in front of her, rather than what she picked up subconsciously before meeting Clara, ie that she is dead and what we have is a ghost or echo of some kind?
Also - what is Clara's role? Alec Palmer says to Emma "You gave me a reason to be, you brought me back from the dead". The Doctor, to all intents and purposes, is dead in the eyes of his enemies. He has been wiped from every database etc, thanks to Clara - and after losing Amy and Rory he has been playing dead, or at least dormant. There is no spark to go off exploring, which is what he gets when he has a companion. The mystery of solving Clara is bringing the Doctor back from the dead - he is travelling again in time and space, with her at his side. Is this also foreshadowing that she will cause him to do something that means he is remembered again across the universe? That he literally comes back to life for all his old enemies? Or just that she helps him rediscover his love of travelling and exploring across time and space?
Finally, big play about lovers/couples and distant descendants. Is Clara a message from River, to get her boy back in the game he so loves? Or their progeny? Lots to mull, in retrospect.