(at around 1 min) In the first scene that Tony gets picked up by the boys in front of the candy store to head to the disco, it is clearly seen that the driver of the '64 Impala is in fact a stuntman instead of Bobby C, whose voice is dubbed in and then appears as the driver in the interior car shots.
When Bobby asks Frank (the former priest) about getting a papal dispensation for an abortion, the camera angle changes so that the side of Bobby's face is shown and all of Frank's can be seen. Frank answers Bobby and then Bobby says "Well maybe you can, maybe you could do it for me." At this point, Bobby's mouth is clearly not moving except once, which indicates that his retort was dubbed in over a one word retort.
When Tony and Stephanie go to dance to Tavares' version of "More Than a Woman", Tony places the needle on the record, and the arm skips all the way to the end, revealing that the record player is broken and the music dubbed in later.
On the first disco night, there is a shot of a bar, which we see a dancing women, bartender, three men sitting at the bar, and another man at the bar wearing a tan suit, he is reflected in the mirror behind the dancing lady. These same people are shown in the same place on the second disco night, both nights when we see them the song "If I Can't Have You" is being played.
In the opening sequence, Tony walks down the street and it's visibly sunny and the pavement is dry. Then when he runs across the street toward the paint store, the street and sidewalk are wet from rain.
The night they take the priest to the club, Tony starts dancing solo (to the song "You Should Be Dancing") and the dance floor clears. His dance partner Connie (the woman in the green dress) is stood up by the stage and standing in place, as are the rest of the dancers off the dance floor as they watch him dance. The lady in the green dress briefly disappears and reappears between shots.
When the (former) Father Frank Jr is leaving the Monero household to go to a settlement home in the first shot, the car he is about to enter is a Ford Country Squire (full size) station wagon. In the next shot when he gets in the car and it pulls away, it is a different car: a Ford LTD II (mid size) station wagon.
When Tony is walking down Brooklyn's 86th Street with the paint can, he walks toward the Benson theater marquee. After he hassles the young lady, he walks away from the Benson, back the way he was coming from.
The required (white square) NYS safety-inspection sticker appears and then disappears and then reappears from the lower driver's corner of the windshield of the 1964 Chevrolet Impala that the boys drive.
At the White Castle Burger restaurant Joey jumps on the table and a lady customer with a green hat walks quickly away from the counter. In the next shot, she is back where she started and walks away again.
When Tony first enters 2001 Odyssey, the doorman (gray vest, glasses) stamps his hand and Tony greets him. In the next shot, when Tony moves into the main hall, the doorman is already standing there and Tony shakes his hand.
Just before the guys crash into the Barracudas' hangout with Bobby C's car, the car windows are down. After they crash, they open the doors, and the windows are up. When they get back in the car, the windows are down again.
When Tony asks his boss for an advance on his pay as they are closing the paint store, it is dark outside. In the next shot, when he is running down the street to his house after work, it's still early afternoon.
At the final bridge scene when Bobby C is climbing up the cables of the bridge, he has on white sneakers. Moments later when he's talking to Tony on bridge's beam he does a headstand and he has on black shoes.
Just after the opening sequence, Tony is dealing with a customer who is painting his room. When the camera is focused directly on the customer's face it is clean, whereas when the camera is focused on Tony and we see a side angle of the customer there are paint smudges on his face and neck.
At two different times, same establishing shot of car approaching Verrazano Bridge is used, even though position of passengers and their clothing should be different since scenes took place on different nights.
Near the end of the movie, Stephanie lets Tony into her apartment. Tony walks in and stops in front of a yellow chair and in front of the first window. In the next shot, he is behind the yellow chair and in front of the second window.
After Tony and Stephanie go out for coffee/dinner for the first time, they walk down the sidewalk together and it's dry out. Just minutes later, Tony drives down the street with his friends and drops one of them off, and the streets are wet.
While Tony and Stephanie are sitting at the windows in Stephanie's apartment, she reaches out and grasps Tony's left hand with her left hand; but when the camera jumps back, she's holding his left hand with her right hand.
When Tony wakes up after the first night at the disco, he sits up. He has nothing in his hands after scratching himself. After a moment he stands and the scene cuts to a shot of the mirror. In the mirror you can see smoke and briefly a cigarette in his hand that had not been there. He then puts the lit cigarette in an ash tray on his dresser.
After Tony leaves the "Disco Duck" dance lesson, he introduces himself to Stephanie. He asks her if she is practicing to be a bitch. She turns her head to him, then the camera angle changes. She is facing away and turns around to face him.
While Tony does his solo dance the girl he was dancing with(Connie) is standing in the background. During the dance between camera shots she disappears for a moment and then reappears at the same spot a few seconds later.
When Tony is first picked up in the Impala, as the boys review their inventory of pills and alcohol, the camera rigging can be easily seen reflected in the passenger window where Tony sits, especially as a lighted "TRAVEL" sign passes by.
Just before Tony gets off the subway train the first time, "45th Street" station signs are visible from inside the car. After he's gotten off the train, he is waiting for a train at "53rd Street". Neither station is a transfer point in the NY subway.
Near the end of the film, during the "How Deep Is Your Love" music sequence, there is a time-lapse sunrise over the Brooklyn skyline. The shot is taken from New Jersey or Liberty Island. Some mistakenly believe it to be a time-lapse sunset (in reverse) or a sunrise over the Manhattan skyline.