Kersey's first shooting victim is hit in the abdomen, but a police investigator at the crime scene the next morning refers to a bullet hole in his chest.
When Paul Kersey is about to be robbed in the subway wagon, a big brown shopping bag can be seen. In the next scene, when he leaves the wagon, the bag is gone. It is the same shopping bag that is later referred to in the police station.
When Frank Ochoa interviews the mugging victim after Paul Kersey shoots dead the three thugs in the alley, the victim's hat appears and disappears between shots.
During the funeral, there is a shot of Paul with his daughter and son-in-law. The next shot is of Sam and Ives with their spouses holding an umbrella. Next to the four of them is an extra in a brown coat, blue pants, and white shirt. The next shot shows the priest reading from a Bible, and here, the same extra is seen in the background on the opposite side of the group.
After Kersey shoots the two muggers in the subway station and is stabbed in the shoulder, there is neither blood on his coat nor a tear in it when he is seen to sit in the subway car to make his getaway.
The gun case given to Paul Kersey by Ames Jainchill has a plaque on top that reads: "To PAUL From AMES," but the character's name is spelled "Aimes" in the credits.
When Ochoa has a locksmith pick the lock to Kersey's apartment door, he breaks the law, as he does not have a warrant. The gauze with the blood taken by Ochoa could never be used against Kersey if they charged him in court. Any half-decent lawyer, or even a paralegal, would know this.
When Ames Jainchill (Stuart Margolin) and Paul Kersey (Charles Bronson) are at the gun club, Ames hands Paul a black powder pistol stating it is an '1842'. Ames is incorrect. When Paul takes it and lifts the gun to shoot it down range, it is clearly a Remington model 1858 black powder pistol based on the Fordyce Beals patent of September 14, 1858 (Patent 21,748), produced by Remington Arms from 1862-1875.
Kersey at the range fires a what was called a .44 cal percussion pistol. This is a muzzle-loaded pistol that uses Black Powder. When fires it, it produces a lot of white smoke; so, what he actually fired was a .44 cartridge in a cartridge conversion kit for that pistol.
When Inspector Ochoa says that the first mugger killed by Kersey was carrying a clip, he was not, as some suggest, referring to a magazine used in an automatic pistol but rather to a holster clipped to his belt which held the revolver.
One of the three thugs has a pistol aimed at Kersey as he approaches them. It seems that Kersey should not have had time to pull out his own gun without the armed thug taking at least one shot himself; however, people under pressure react differently, and it's possible, even likely, that a young punk might have reservations about shooting someone. That hesitation might be sufficient for the "victim" to pull out their own weapon and fire.
Throughout the movie, the same People Magazine cover with Ochoa on it is seen. People publishes weekly, and as the film takes place over the course of several weeks (presumably), it is unlikely that the same issue would continue to show up, especially at the newsstand in the film.
The sound of the breaking car window is of standard glass, not safety glass.
When Ochoa meets with the District Attorney and the Commissioner in the DA office, the DA offers both of them a bowl of jelly beans to choose from. Anticipating a grab for jelly bean, Ochoa pulls his hand from his pocket before he's even shown the bowl.
As Freak #1 enters the room to grab Mrs. Kersey, he flicks the painting on the wall with his finger, sending it swinging.
When Paul and his son-in-law look out the window at the hospital, they are seen through the glass. In the reflection, there's a barely visible large black square. When the camera dollies left, the square follows, indicating that the square is there to disguise an all too recognizable camera silhouette.
The first shooting victim is supposed to be close to Kersey's home 2 1/2 blocks from where he shops around West 75th Street. In reality the steps he descends are at West 99th Street about 1.25 miles away.
The police detective tells Kersey there is little chance the killers would be caught. The home invasion, however, reveals the perps left their fingerprints everywhere -- the stairwell, a door frame, the door knocker, and inside the apartment.
When Paul test fires the guns at the gun club in Tucson, he is clearly careful about putting on hearing protection, yet he does not put on any eye protection, which is required at gun ranges. Ames puts on eye protection yet he isn't even the one shooting at the time.
The look of the Kersey apartment, with its clash between gaudy and plain, radically mismatched furniture, wall art, and other elements, is so hideous (even for 1974) that no architect (and no one with any sense of design) could bear to live there.