Plot hole: The mob hitmen are about to enter the Sweeny family's house to kill them when the police van arrives to move them to a witness protection safe house. In the next scene, the bad guys abduct Catherine and try to force her to reveal where the Sweenies have been taken. Why? They could very easily have waited and simply followed the van.
Plot hole: 3-11 "The Reckoning": Vincent reveals the underground kingdom to Diana for what is meant to be the first time. But she was already there twice in the previous episode, which was definitely not shown out of chronological order. She was taken below by the helpers to meet with Father, and was there again at the end when Vincent christened his son "Jacob."