Continuity mistake: Benson visits Stabler at his home to confronts him about the FBI detail he has ordered to protect her. They talk outside and then Benson is seen walking away. The next shot shows a side shot of Benson approaching him again in silence but mouthing words to him. (00:49:00)
Guy Walks Into a Psychiatrist's Office - S2-E1
Plot hole: In this episode Tony tells Janice that he has just put their mother's house on the market. In season one, the house had already been sold.
Suggested correction: Tony and others say many things that aren't accurate. While season one gives the firm impression that the house is sold, it's not confirmed on screen. There may have been a deal where the intended buyer couldn't get financing or a closing never took place for other reasons.
Revealing mistake: At the end it is not Helen against the filing cabinet - the face is different. Obviously a body double.
Character mistake: In the final episode, Carlos visits Doc in the psychiatric hospital for advice concerning his upcoming marriage to Holly. While talking, Carlos refers to Doc's deceased wife as "Linda", while throughout the series, it has been made very clear that her name was Deborah.
Continuity mistake: Emma falls off the roof and into a water butt when she is being chased by the villains, the police pull her out and she is soaking wet. A few seconds later she screams when the villain catches Nicola, and when they fall through the roof she is dry.