When Jack shows Nadia the picture of Irina holding her niece as a baby, the picture originally shows Irina holding her in her left arm, in the next shot it shows her holding her in the right arm, and then switches back to the left
There are two different photos of Nadia and Sidney's mom with a baby from the past. The one Jack looks at, the baby is in the left arm facing right. Then Nadia looks at the photo and the baby is in the right arm facing left.
Kellie MacDonald is from Glasgow and has a strong Scottish accent, while Mark Aiken, who hails from Belfast, has a soft Irish brogue. Yet they play characters who are supposed to be brother and sister.
The picture Nadia asks about, with Irina holding a baby, switches from the baby being held with the head on the left, to when Jack asks to see it, it's switched to the right.
Sloane tells Nadia that his affair with Irina was "brief". However, given that he once thought Sydney might be his daughter and that Irina left while pregnant by Sloane when Sydney was six, the affair must have been lengthy.