After Seth and Chris have their argument in the stairwell right off of the boiler room, Seth goes down at least one flight of stairs on his way out. In the next scene he passes Abby in the receptionist area that is on the same floor as the boiler room - because he's been bumped upstairs to nicer offices.
Having known the FBI are going to raid the office why would Seth go to Chris to ask him to sign a sell ticket so Harry Reynard could "dump" his shares on the open market and make his money back. Seth confirms this goof by saying "what's the difference?" The FBI would cancel all transactions made long before the raid, the same goof occurs when Seth asks Michael if they can give Harry Med Patent IPO, also before the raid knowing ahead of time the FBI was going to raid the offices.
If Jeff hired additional help to keep the casino running full time, Seth would have already known about it because the casino is in his apartment, he still has to go in and out when the casino was open.
When Abbie refuses to cooperate with the FBI, they remind her that her name are on all the sell tickets and she's the one putting all the deals through, she's only one of the secretaries, she has no involvement in the actual transactions of the stocks being sold.
Greg tells Michael he has a list a clients that have taken heavy losses and continued to trade stock with him, that makes no sense because no client would continue to do business with a broker and their firm if they're constantly losing money.
When Greg gives Seth his first orientation meeting he tells him each potential client card has only their name occupation, and phone number, however when Seth attempts to pitch Harry Reynard he asks him what he does for a living.
When trying to save his father's career Seth says it'd be worth going to jail for, however he was charged with violating of 26 FCC, and NAS regulations, his only under the assumption he would go to jail, the judge would be deciding factor for his sentence.
Jim begins the orientation interview with the new recruits by telling them we expect our coworkers to treat each other with a certain level of respect, yet throughout the film we see and hear the brokers constantly berating and belittling each other with profanity and other remarks and gestures.
When Seth is driving on the Long Island Expressway he says he goes to his interview off exit 53. In the next frame you see Seth driving on Northern Blvd. which is exit 32. Further in this scene we see Seth driving on Northern Blvd. east but then cuts to a scene where he is traveling west on Northern Blvd. which would make him driving the total opposite way of where he wanted to go.
When the FBI arrests Seth, they tell him to go to work the next day and copy his C Drive onto a floppy. This would be impossible as a floppy disc only holds 1.5 megabytes and his hard drive would hold Gigabytes, at least.
When Seth closes an account before receiving his Series 7, Greg becomes angry and tells Seth that he'd violated several SEC laws. However he closes Harry Reynard a short time later, and still hasn't passed the test.
When Seth's father calls him to say that he would go in with him with the IPO scam he states first that "I'll make sure you won't get caught" and then "I have a friend..." While the FBI playback is different, since this wasn't court testimony, they may have been using an altered tape.