I didn't add this to my main post articulating my theory that Derpy is Clara Oswald because it didn't fit with the flow of the feng shui. However, it's amusing enough that I've given it its own brief post.

In the 6th episode of the Doctor Whooves and Assistant series, the Doctor and Derpy get into a heated argument. Near the end, we get this exchange:

Within a span of 40 seconds, Derpy alludes to three fundamentals of Doctor Who:

• She unintentionally brings up his status as a grandfather.
  
• She points out that he doesn't give his name.
  
• She correctly deduces that he stole the TARDIS.
  

Now we jump to this encounter between Clara Oswald and the First Doctor:

http://www.youtube.com/watch?v=kXZXbBK3B6k

Clara helped the Doctor steal the TARDIS (*ding*) with his granddaughter (*ding*) in the opening of an episode aptly titled The Name of the Doctor (*ding*).

If Derpy is merely another copy of Clara, it's possible that within this long-winded argument she had a subconscious memory of actually helping the Doctor steal the TARDIS in another life.

Note that these tangents of Derpy's sequence of Doctor Who references were directly after the Doctor insults her love of muffins and brings her mother into it. Remember that muffins are the substitute for soufflés in this alternate dimension incarnation of Clara. In the aforementioned Who episode, Clara reveals that her love of soufflés stems from her mother. In fact, right before she jumped into the Doctor's time stream, she invokes her mother's soufflé philosophy.

I believe that if anything were to trigger a quasi-memory in Derpy's mind of helping the Doctor steal the TARDIS, it would be the mention of muffins and her mother.