Visible crew/equipment: When Neil (De Niro) breaks into Van Zandt's apartment and shoots him, watch as Van Zandt flies backward. You can see a wire running up through the bottom of his sweat pants.
Continuity mistake: When De Niro confronts Ashley Judd in her motel room, he knocks all but a few hangers off of the metal coatrack. While the camera goes back and forth while they argue, the remaining hangers disappear and reappear several times.
Continuity mistake: In the shoot-out after the bank heist, Vincent's rifle starts out as an AR-15 style with a carry-handle, but by the time he catches up to Mike, it switches types and has no carry-handle.
Continuity mistake: In the scene where Al Pacino is confronting Hank Azaria about his relationship with Ashley Judd, the position of the knot in his tie changes during the scene. (I saw this error noted under "corrections", but if you watch closely, the knot is almost completely under the left collar tab of his shirt between shots.)
Visible crew/equipment: When Neil is sneaking up at Van Sant's house, you can see both Neil's and the camera man's reflection in the glass windows on the house.
Continuity mistake: When the agents are doing surveillance on the hotel room, they have a camera connected to the "peep hole" on the adjacent door. There is a TV monitor that the agents are watching. When the agents open the door to leave the room, the door with the camera on it opens, but the picture on the monitor stays the same.
Continuity mistake: In the scene where Neil is coming out of the elevator at the hotel Waingrow is staying at, you seem him switching his flashlight to his right hand while he reaches up with his left hand to set off the fire alarm. In the next shot, we see a close-up of his RIGHT hand setting off the fire alarm. The shot after this, you seem him lowering his LEFT hand from setting off that alarm, with the flashlight still being held in his right hand.
Visible crew/equipment: In the drive-in shootout scene, the camera and crew are visible in the rear view mirror in the cab of the white Dodge pickup fleeing De Niro and Kilmer.
Other mistake: In the scene where Pacino is talking with Albert outside, when Pacino starts singing, the soundtrack on Albert's dialogue is way off.
Continuity mistake: In the scene where Ashley Judd is giving Val Kilmer the "risk versus reward" speech, her hair goes from being neat to messy between shots.
Visible crew/equipment: When Vincent Hanna decides Neil is already gone, he heads to his hotel room. He enters the room and walks out onto the balcony. The shot of him approaching the balcony and opening the sliding door is shown from outside, on the balcony itself, and the cameraman (wearing a white shirt) and camera are visible reflected on the left side of the sliding glass door. It is more evident as the shot progresses, because the cameraman shifts position and the reflection moves further to the left, becoming larger.
Continuity mistake: The armored car robbery takes place in the early morning. Waingrow pulling on his clothes, the light in the sky all say early day. By the time Pacino arrives to survey the scene it's pitch black and all the bodies are still on the ground.
Continuity mistake: Robert De Niro finds Val Kilmer in the apartment and they are discussing Kilmer packing it in. Kilmer is all stressed out, and decides to light a cigarette - using a Zippo lighter. The sequence of events is: Val Kilmer grabs a cig, smoke rises from the cigarette, THEN you hear the click of the Zippo lighter.
Continuity mistake: After the first wave of police cars does the "demolition derby" across the spike strip, they show some cops running out to stop the next group of cars. When they do that, the spike strip is not in the street. Then the scene shifts to a close up of the cop cars skidding to a stop directly in front of the spike strip, which has now re-appeared.
Continuity mistake: When Neil sets off the fire alarm in Waingro's hotel, there is a little red sign above the fire alarm when shown from far away. When it shows his hand up close pulling the alarm, the red sign is gone.
Continuity mistake: When Vincent is sitting at the table drinking whiskey and talking to Justine, the remote control, the bottle, the glass, the bottle cap, and the chicken leg all keep changing positions. Yes, he does pick up some of these items, but right after he drops the chicken leg to the table, the camera switches to Justine. 2 seconds later, it goes back on Vincent and all those items have moved at once.
Revealing mistake: When Neil & Co. are in the restaurant after the armoured car robbery, they all get up to leave to deal with Waingrow. The next shot is from the parking lot of them leaving the restaurant. Right as the shots switch, they are all standing still lined up at the door for a second, and then they start to move out the door (once the director yelled "Action" I'm sure).