Plot hole: The scene in Central Park where Bud tapes Gekko never would have happened. Gekko's comments imply that he was unaware of Bud's arrest earlier that morning (not just that Gekko was unaware he was being taped). (1) Gekko makes comments that the Feds are pleased with, at least to some extent incriminating himself. (2) Gekko doesn't say something like: "OK, now you've been pinched, here's what you do." BUT - how in the world would Gekko not know of Bud's arrest? Even in the days before the internet, information spread like wildfire on Wall Street. All the brokers in Bud's office would be on the phones saying "they just arrested Gekko's broker!" Everyone on Wall Street, especially someone like Gekko, would find out, and far more quickly than the time it took to schlep Bud up to Central Park and strap a recorder on him.
Plot hole: One of the children is a witness that saw the man that planted the bomb in Dixie's house. He is said by a policeman to have been playing 'under the porch' and was close enough to make-out the Special Forces tatoo on the bomber's arm. Problem is, Dixie's house had no porch of any kind, and any other home's porch would've placed him too far to see such a small tatoo so confidently. (00:57:40)
Suggested correction: The rear of Dixie's house is never shown. The house could conceivably have a back porch the kid could have been playing under and the killer could have used the back door.
Plot hole: When Murphy is in the changeroom at the station, he learns that an officer has just died and that his funeral (according to the captain) would be the next day. There's simply no way a funeral can take place one day after someone's death. All the planning, prep work and getting the body released to the funeral home would take about a week...plus many other things. Simply cannot be done.
Plot hole: After Margaret kills Mike at the end, she leaves through the door that is right next to his corpse, leaving her fingerprints on it, since she is not wearing any gloves. Under these circumstances, the police surely would have done some forensic investigation and dusted the doorknob for prints, which would lead back to her. Considering Margaret moved up from being a psychiatrist to a lively con criminal, you'd think it would occur to her to clean up a little bit, but she gets a happy ending.
Suggested correction: As she tells Mike, she's out of control. I don't think she planned to kill him, but he goads her into it by telling her she really hadn't learned anything and he played her. THAT was the point she learned the lesson. She took the risk and killed him. The doorknob fingerprints were a risk, but not much of one since a lot of people probably used that door before the police got there.
As for many people using the door after the murder, probably only one person might have used it if they opened it from the hallway side, only touching the hall side knob. That person would have immediately seen the body and called the police. Anyone on the baggage handling side wouldn't have touched the doorknob. Still, Margaret is not in much peril from fingerprints, since we are led to believe she has always been a "good person" who would probably never have had her fingerprints taken.