- Wolff's handler Justine repeatedly saying 'heavy sigh' instead of actually sighing turns out to be foreshadowing the fact that she can't actually talk out loud, and is using a text to speech converter.
- The Treasury Department is an unusual choice for an investigating agency in a Hollywood film, versus more typical choices like the FBI, CIA, or police departments, but it makes perfect sense given what the protagonist does for a living. It also makes for a handy setup for an Elliot Ness joke.
- Agent King & Medina also actually use resources outside the Secret Service. Medina uses a contact at the Department of Homeland Security to start her investigation with facial recognition, follows up with FBI Language Services, presumably goes across to an IRS staffer (same Department but different agency) to run through the aliases, then has FBI agents with her & King when they find Wolff's house.
- All these Federal agencies working together like some sort of league of justice. Batman jokes aside, it's interesting to note that this level of interagency cooperation would have been less likely encountered in a film before the War on Terror and the attention it brought to the dangers of Interservice Rivalry.
- The bit of dialogue where the film's Title Drop comes in has Medina asking for clarification, with "like a CPA?" only to be told that's not quite the case. Given that Wolff works off the grid under a variety of false identities, and even learned the trade in prison, it is certainly unlikely that he's a Certified Public Accountant, at least not under any name he actually uses for business.
- Wolff has a tendency to go on a Roaring Rampage of Revenge whenever the baddies threaten anyone he has a personal connection with, not just the love interest. One of his father's biggest rules was that you are always loyal to your family. It seems that given his social difficulties, Wolff includes anyone he's managed a connection with, even platonic, as part of his family and acts accordingly.
- Filming the O.O.C. Is Serious Business scene showing the mis-timed driving of a car into a garage would have required precision timing and plenty of rehearsals.
Fridge / The Accountant