(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".
(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 45 mins) At the original interview, Dr. Molly asks Aaron "How did you meet?" and then she asks "What was the relationship like?". When Marty is watching the interview tape (at around 1h 35 mins), Dr. Molly, after asking "How did you meet?" says "Doing what?".
(at around 1 min) In opening credits Naomi ties Martin's bow-tie (same as tying your shoes) and does so over the points of his butterfly collar. He turns to the bathroom mirror where he checks it and adjusts the bow-tie, but leaves it holding down the points, and nearly walks out the door. But when he turns with an afterthought the points are instantly positioned correctly.
(at around 31 mins) The blood at the scene of the murder (where Vail comes in some days after the murder), and the blood on Aaron's sneakers, shown in the court, should be brown, because some time has passed and blood coagulates. When blood coagulates it turns from red to brown.
(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.