When Trudy meets her father outside the music store, she gives him the slip and jumps in her dad's chauffeur-driven car and tells him to go to the Waldorf Towers. In the next scene, Trudy and her dad are walking in the park together with no explanation of how they meet up again. Later in the movie, Trudy's mother comes to town from Florida and stays at the Waldorf Towers. It appears the scenes are out of sequence.
When Jim handcuffs himself to the bed during his eviction, he places one end of the handcuff on a vertical bar of the bed's head railing. In the newspaper picture later, the end of the handcuff is attached to the horizontal railing.
When Trudy is playing the piano while singing, her arm movements do not match the song's tempo or the notes being played on the piano.
After Farrow finds O'Connor shoveling snow, they have a discussion inside the car regarding the land purchase. Farrow tells O'Connor that someone had bid $195,000 for the land and O'Connor orders him to bid $200,000. Later, Jim complains that someone had upped the bid to $190,000 without mentioning either the $195,000 or the $200,000 bid.
Early in the movie when McKeever crawls into the mansion, the handle on the manhole alternates between up and down between shots.
Jim's picture in the newspaper during the eviction shows him handcuffed to his bed against the background of his apartment wall. There were no photographers in the eviction scene, just movers who picked up the bed and carried him out of the building.
Mike carries the telephone into the walk-in freezer and closes the air-tight door, which would have cut the phone cord.
When McKeever is walking with the dog there is a street pole with a sign reading "E.79 ST." printed small and "5TH AVE." printed large on the same plate. In reality, the street and avenue would not share the same plate or placard. They would be separate signs perpendicular to each other or facing different directions, and they would be the same size print. Additionally, it would simply read "5 Av" and not "5th Ave."
As the boys are throwing O'Connor into the closet, the back wall of the closet bends under pressure, showing it has a false background.
When Trudy fakes fainting she has her head turned to the right side. However, in the next cut which is a close up her head is facing straight up. Additionally, she opens her eyes and did a smirk. However, McKeever is attending to her the whole time and looking at her therefore he would have noticed Trudy's aforementioned gesture.
Alice recounts her proposal seven years earlier at a Gregory Peck film. Peck's first film was in 1944, only three years before the movie is set.
Mac rigged the house so that if anyone came in through the front door, the electricity in the house would be cut. When Mike entered through the front door using his own key and when the patrolmen entered on Christmas Eve, the electricity to the house was not cut.
If there had been family photos/art in the mansion, surely the two homeless gentlemen would have spotted that their new guests, "Mike and Mary," were the rightful owners of the mansion.
Once the two families and the dog moved into the house, the nightly guards weren't mentioned again until they showed up again on Christmas eve, toward the end of the film.
During the time when everyone is "secretly " occupying the O'Connor mansion, there is constantly a fire burning in the fireplace, but no one on the outside, not even the guards, sees or smells the smoke from the chimney.
They couldn't possibly bring in that huge Christmas Tree through the fence or manhole. Bringing it through the front door would have blown their cover.
When Mr. McKeever first enters the O'Connor mansion, he sets the grandfather clock without checking first to see the correct time.