Plot hole: (Episode 4.13 - Reefer) Throughout this episode, due to certain threats by Escobar and his drug lords, McNamara/Troy has been ordered to have around the clock FBI security detail, including "dozens of hidden surveillance cameras" inside the premesis. However, later in the episode, Ms. James and Michelle (who both would later turn out to be working for Escobar) poison, kill, then dismember the homeless guy named 'Reefer' to use his organs for Escobar's organ harvesting ring. Various FBI agents stop James and Michelle outside as they try to leave the premesis carrying big duffel bags of the dismembered patient and don't suspect anything. But wouldn't have all those "internal surveillance cameras" (that James and Michelle didn't know about) inside the office have easily exposed the murder and dismemberment of Reefer?

Factual error: (Season 4) During the episode where Ms. Grubman and Christian are talking in his office and he turns around a few seconds later to see she had died while in her wheelchair, her head and posture is still straight up and forward - near impossible. Common physics tells us that upon death, her head would have either drooped backward, downward, or to one of her sides.

Other: (Season 4, Episode 1) During the scene where the phone sex operator lady is having her voicebox operated on, you can see on at least three different occasions her eyes flinch and squint. Obviously, she was "awake" when this was filmed, but during a normal procedure such as this, she should be completely sedated and she would not be flinching her eyes.

Other: In the episode "Conor McNamara", Mrs. Grubman is lying in the coffin. She noticeably swallows when she is supposed to be dead.

Revealing: (Across Season 4) During several close-ups of baby Conor McNamara over various episodes in Season 4, you can see the off-colored slip-on "gloves" that are used to represent Conor's deformed hands.