Continuity mistake: Rachel the journalist puts on her jeans twice when speaking to Reddington.
Alexander Kirk: Conclusion - S3-E23
Continuity mistake: When Tom Keen returns from shopping to find someone over the cot of baby Agnus, a fight breaks out, during which the camera jumps to different shots of the baby who is wrapped in a pink blanket, then no blanket, then back to wrapped in the blanket. (00:37:22 - 00:37:58)
Continuity mistake: The knife hole and blood on the envelope of the note to Scottie Hargrave changes. In the first close up, the name is aligned to the middle of the hole and there's a trail of blood running down towards the corner. In Scottie's hand, the hole/blood is higher up and the trail of blood is gone.
The Troll Farmer (No. 38) - S3-E1
Continuity mistake: When Solomon forces Isabella to take a photo of her baby and send it to him, the picture she takes is different to the one he receives. Note the position of her baby's hands and stuffed Panda.