Mick is on his cellphone with Maggie just before he enters his house. She tells him that their daughter has soccer practice on Saturday. He replies "Saturday," and nothing else. Mick discovers the door is opened and Roulet is inside. Having overhead the conversation, Roulet asks Mick to confirm his daughter has soccer practice on Saturday. Unless he has incredible hearing ability, he could not have overheard what Maggie said.
As Haller is leaving the court after Roulet's arraignment, he tells Dobbs they'll meet at Dobb's office at 4 pm. When Roulet approaches Haller and Levin in the lobby of the law office, Haller says "Good Morning" not "Good Afternoon."
When Haller gets back home after getting Roulet acquitted, he pours himself a glass of Jack Daniels. However, in the previous shot when he walked in the door, the glass was already filled.
After Nick gets the parking ticket, he puts it in his right breast pocket. When he gets home he reads it again, but he pulls it out of his left breast pocket.
At 24:00 minutes, Charles Talbot is shown leaving the apartment. He has his shirt fully unbuttoned and is tattoo is showing. Scene cuts back to car and then to Talbot, and this time his shirt is partially buttoned.
Towards the close of the film, a commuter train is visible at a railway crossing. While the train is clearly electricity powered (pantograph and overhead power cables are visible), the sound of a diesel locomotive is heard. But sound can come from anywhere - not merely where the camera is pointed, so the quiet train isn't the source of the off-camera sound.
When Haller comes home and finds his door ajar, the door opens inwards with the hinges on the left hand side (as viewed from inside the room). He then confronts Roulet and escorts him from the house through a different door whose hinges are on the opposite side.
The license plate on Mick Haller's car is NTGUILTY. California plates only allow for seven letters/numbers. NTGUILTY has eight. The 'I' appears to be a gimmick added afterwards by Mick (or a friend) as it lacks the serifs a stock CA license plate would give an 'I', but there is too much space between the 'U' and 'L' for this to otherwise be a stock plate.
At the end, Earl starts the car and immediately places his right hand on the steering wheel, without ever putting the transmission into gear.
At 1:26:30, prosecutor Minton asks the court for time before he rests his case. However, earlier at 1:20:10, Minton declares that "the State rests, your honor."
They mention early in the movie that Louis is apprehended by the two gay guys (Reggie's neighbors). Neither the prosecution nor the defense calls them to the stand as witnesses.
The police couldn't have known or expected Louis to lie about the knife. They would have expected him to immediately tell Haller the file was fake.
Maggie chastises Haller for not revealing that he owns the make & model of gun used to kill Frank. She must know the story about the gangster giving it to Haller's father from back when they were married.