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 mistake: (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.
Continuity mistake: In the 5th season, episode 15, Christian is supposed to have several bruises and a broken clavicle, so he is wearing an arm sling when he is talking to Sean. After Colleen attacks Sean and locks them (Sean and her)in the office, Christian pushes the door. and when he finally opens it, sees Sean on the floor almost dead, In this scene he is not wearing the sling, and is moving the arm perfectly (when he's supposed to have a broken bone) and there are no bruises.
Other mistake: In episode 5-21: "Allegra Calderello," Allegra discusses with Shawn and Christian the fact that the show-within-a-show, "Hearts and Scalpels," featured a character based on her, called "pussy lips" because Allegra had her lips reconstructed with her labia. However, in episode 5-1: "Carly Summers," Shawn and Christian referred to their one-time patient as "pussy lips," but the network censors refused to air the word "pussy," and the euphemistic phrase "lady cha-cha" was used on the air instead. So Allegra would never have seen a character called "pussy lips."