- She does not drive: "I've attempted and failed two or three times. I'm one of those people who's nervous behind the wheel - nervous of hurting anyone. I shouldn't be on the road, basically." Whenever a character that she plays is required to drive, the shots have to be faked with the car on a low-loader.
- Is one of sixteen regular EastEnders (1985) actors to have appeared on Call the Midwife (2012) either in a main or a guest starring role. The others are Cliff Parisi, Lorraine Stanley, Tilly Vosburgh, Lacey Turner, Jenna Russell, Kacey Ainsworth, Matilda Ziegler, Ted Reilly, Jasmyn Banks, Danny Walters, Lucy Speed, Kate Williams Anita Dobson, Scarlett Alice Johnson and Ann Mitchell. Of these sixteen, O'Neill is one of twelve actors to have appeared on Call the Midwife (2012) after appearing on EastEnders (1985).