In retrospect. When O'Donnell rattles off the names of the Doctor's companions, it's telling that she doesn't mention either Donna Noble or Clara. Both being companions who are impacted by a memory wipe, directly or indirectly. Note that O'Donnell, despite being familiar with Rose, Martha and Amy, does not recognize Clara when she meets her in person and is never seen conversing with Clara about the Doctor.
Fans familiar with sign language have noted that, despite the Doctor's claim to have "deleted" it from his memory, he actually signs "You're beautiful" to Cass, which granted is not what he meant to ask her. A more subtle one occurs later when the Doctor talks to Clara about his "duty of care" towards her and appears to make the ASL sign for "I love you". This appears coincidental until one recalls that at the end of the season the phrase "duty of care" is explicitly positioned as one of the Doctor's many euphemisms for "I love you".
