Continuity mistake: Diamond is backing his convertible up to drive away from the crime scene. He turns to look behind him and places his right arm on the top of the seat. When the shot cuts to a wider angle, his arm is suddenly in a different position, draped all the way over the back of the seat.
Continuity mistake: When Diamond pulls his car up across the street from Sutro & Son, the building behind him is in shadow. In the next shot, as he parks, it's in bright sunlight. When he gets out and crosses the street, the shadows are back.
The Fine Art of Murder - S4-E16
Continuity mistake: Diamond comes in to an alley and sits up in front of a white crate. When the angle changes, he sits up again, and now the crate behind him is black.
Continuity mistake: The bad guy backhands Ted, striking him across the right side of his face. Later, when Diamond questions him, Ted has bruises on the left side of his face.
Fallen Star - S4-E19
Continuity mistake: Diamond takes a full cup of coffee from the vending machine and walks down the corridor with it as he talks to Mark. He takes only three brief sips from the cup before turning to leave. There are no time gaps in the scene, nor is there anywhere for him to have poured the coffee out, yet he tosses an empty cup into the trash on his way out the door.
Continuity mistake: The hitman fires at Diamond and the bullet strikes a post beside his parked car. In the next shot, as Diamond races into the alley after the gunman, the car is in the background, but the post has disappeared.