The video recording of both psychiatrist's interviews with
Aaron do not match the meetings we originally saw.
Martin's cut over his right eyebrow appears and disappears.
(at around 1h 25 mins) While Vail, Tommy, and Naomi are discussing the porno tape, the blue screen of a computer monitor is reflected in Tommy's glasses. But in the reverse shot (showing Vail) the monitor is off.
When Vail is in the bar drinking shots and talking to the reporter, first he is shown to be sitting on the left of the reporter, then on the right (with the TV to his left), then back on the left (with the TV to his right).
At around 01:16:50 when Roy is grabbing Vail, one can see that he already has blood in his right eyebrow before he is smashed against the window frame, action which supposedly caused the injure.
(at around 1h 19 mins) It is stated by several characters that a plea cannot be changed mid trial. However, it is entirely possible to change a plea before sentencing.
(at around 31 mins) The blood at the scene of the murder (when Vail visits it some days later) and the blood on Aaron's sneakers that are later seen in court should be brown. The iron present in blood oxidizes after being exposed to air, turning the blood rust brown in a short amount of time.
Vail says that for a defense attorney, "you don't ask, you don't care" whether a client is guilty. In reality, attorneys absolutely expect their clients to tell them the full truth, because holding back facts or a confession of guilt can tank a defense. While lawyers cannot lie or allow their clients to lie, determining blame or guilt under specific statutes is complex, and so a lawyer can in some cases still allow a guilty client to plead "not guilty" without perjury. A guilty person might think it better to lie to the lawyer in order to plea not guilty, but since in these cases the truth often outs itself, a lawyer would rather know the truth and seek to mitigate consequences than simply never ask her client for the truth.
(at around 12 mins) Joey Pinero hands Marty a CD of Dulce Pontes, and says that the music he liked is the fourth track. In that album, the song used in the film is, in fact, the first track.
The Chicago PD officers in the film are shown wearing American flags on the right shoulders of their uniforms. Chicago PD uniforms display the flag of the city of Chicago on the right shoulder.
(at around 1h 14 mins) When Aaron pushes Martin Vail against the wall in prison you can see that the wall bends, showing that the wall wasn't made out of bricks or any other hard material.
(at around 24 mins) On film sets, it is common practice to mark a bottle of water with your initials so that it doesn't get lost amidst the sea of other half empty bottles of water on set, especially if you're the PA or AD tasked with babysitting an actor's water. When Martin walks into his living room to watch the news report about Aaron's arrest, he's carrying a bottle of water that is clearly marked with the initial R.
(at around 3 mins) At the Catholic Charities dinner, the Archbishop is addressed as "Your Excellency". Assuming he was a Cardinal (since he was wearing red, not purple) he should have been addressed as "Your Eminence".
Martin tells Tommy "Aaron" should be in a psychiatric hospital not in jail, murder in the first degree sentences are sent to prison not jail.