Crew or equipment visible: When Jimmy is looking for a headstone for Katie, the dolly tracks are reflected in one of the headstones.
Revealing mistakes: After Jimmy put the dress on Katie's body, you can notice her breathing.
Continuity: When Jimmy Markum is drinking whiskey with Celeste Boyle the cap of the bottle is alternately on/off between shots.
Continuity: In the conversation between Jimmy Markum and Celeste Boyle during which Celeste reveals she believes Dave killed Katie, Jimmy's arm is around Celeste's shoulder in close-ups, but off on wider shots.
Boom mic visible: When Jimmy notices his daughter's car for the first time, a boom mic is revealed through the trees.
Crew or equipment visible: When the two "cops" take Dave off in the car in the opening scene, at the end of the street we get a quick glimpse of a local police cruiser blocking the head of the street.
Audio/visual unsynchronized: When Jimmy is pouring himself a drink, the sound of pouring liquid continues, although the level of the drink in his glass ceases to rise.
Continuity: Katie's body is not in the same position when the cops first find her dead and later on when she is filmed for the last time at the scene of the crime.
Crew or equipment visible: When Markum and family are leaving the first communion and they see police cars fly past the church, the shadow of the camera falls across Markum's back as it moves around him.
Anachronisms: As the young Dave Boyle is being driven away by the pedophiles, we cut back to the young Jimmy and Sean standing in the street. In the background to the right, in plain view, is a modern era police car.
Anachronisms: The type of license plate on the car driven by the "cops" in the opening scene, which takes place in 1974 was not used in Massachusetts until the mid-1990s.
Anachronisms: In early street scenes, set in the '70s, there's a "no trucking" sign on a pole that employs the red circle with the line through it. These signs didn't come into use in the U.S. until the 1980s.
Continuity: Near the end of the movie, Jimmy has his hand on Sean's shoulder. In one shot Jimmy's jacket sleeve is at mid-wrist, exposing his sweater sleeve and watch. In the next shot, his jacket sleeve is pulled all the way to his glove, and his watch and sweater are not visible.
Continuity: When Dave is sitting in the dark and speaks to Celeste about vampires near the end of the film, he is watching, _Vampire$ (1998)_. However, as the scene progresses, the movie in the movie keeps switching from one scene to another and back again.
Continuity: In the flashback scene, we see Dave writing his name in the slab of fresh concrete. The camera shows the letter A in the name, but the letter is not completed. When we see the same slab of concrete years later, we can see the name Dave not completed, but the letter A is now fully written
Continuity: When Jimmy pulls out his knife his glove disappears then reappears in the remaining shots.
Crew or equipment visible: When the two "cops" take the kid away at the beginning of the movie, you can see the camera lens and the hand of the operator as the are about to pull away.
Audio/visual unsynchronized: When Dave is writing his name in the cement, you can hear him write a lot more than the first two letters that he actually writes. He writes DA but we hear more stick strokes in the cement.
Continuity: When Jimmy goes to the shop before going to the church for his daughter's First Communion, he takes with him a grey suit. But at the church he wears a brown suit.
Continuity: The angle of the Tobin bridge and the view of the Bunker Hill monument keeps switching the neighborhood from Chelsea to Charlestown many times throughout the movie
Revealing mistakes: When Katie's body is on the table in the funeral home, in one of the shots, her eye twitches just before the shot cuts away.
Crew or equipment visible: Near the end of the film, where Sean pulls away in his car, the scene dissolves into the parade. As Sean's car pulls away, the head of (presumably) the cameraman is visibly reflected in the window.
Continuity: Jimmy's Cross tattoo on his back changes size from small to large.
Continuity: Jimmy's graying temples appear and disappear (at least on one side) throughout the film.
Continuity: When Dave comes out onto the porch to smoke he is startled by Jimmy and drops his match before lighting his cigarette. Cut back to Dave and the cigarette is lit.
Errors in geography: The Cantab Lounge is a folk and bluegrass club in Cambridge, between Harvard and MIT. It is highly unlikely that Boston police would congregate there on any night, much less grab a drink there.
Continuity: When Sean and his partner are in the car talking about how the gun used in the liquor store hold-up by Just Ray relates to the murder, Sean is seen loosening his tie and unbuttoning the top button of his shirt in the car. When they cut to a reverse shot (with the camera on Sean's side of the car) his tie and shirt are done up again. The shot is reversed again as Sean is seen getting out of the car and proceeds loosens his tie while outside the car this time.