Brainwash

At about 18:18, Madeleine appears to wear a similar ring to the one Nikita wore in the intro scene. Nikita used a blue stone one to scan the glass for fingerprints, and Madeleine wears a green one, in the same oval style.

In the phasing shell images, Nikita is shown killing her step father by holding him down and suffocating him. However, in the close-up, Peta's hand is only covering his mouth, while leaving his nose to breathe just fine. This wouldn't kill him, at most it would simply shut him up but---because he is able to breathe through his nose---the man would have had enough oxygen to get up and fight back against Nikita.