Continuity mistake: At the beginning of the episode, Van Gogh starts painting blue circles "on" our TV screen (this is the 3D episode). The three circles are big and touch each other. Next shot, seen from a standard point of view, you see him getting back up and the canvas is still on the floor: the circles are smaller and quite far apart.
Continuity mistake: In the scene where the DA and the deputy mayor are talking outside the DA's office (after she is found sitting in his office with the artist's dad), the deputy mayor closes the door when they exit the office. In the following conversation, the door is ajar.