Rather than dubbing in the gunshots during the bank robbery shoot-out, Michael Mann had microphones carefully placed around the set so that the audio could be captured live. This added to the impact of the scene, because it sounded like no other gunfight shown on-screen.

In an interview with Al Pacino on the DVD Special Edition, Pacino revealed that for the scene in the restaurant between Hanna and McCauley, Robert De Niro felt that the scene should not be rehearsed so that the unfamiliarity between the two characters would seem more genuine. Michael Mann agreed, and shot the scene with no practice rehearsals.

When Kevin Gage was imprisoned for two years in 2003, he was universally addressed by fellow inmates and prison guards as "Waingro", his character from this movie.

In an early draft of the script, Vincent Hanna had a cocaine habit, which, according to Al Pacino, explains his bombastic outbursts.

In the director's commentary, Michael Mann noted that Al Pacino improvised the line "Because she's got a GREAT ASS!" Hank Azaria confirmed it, saying that Al Pacino's unexpected outburst "scared the hell out of me", "he just actually terrified me" and that his look of shock was "not acting at all".

Continuity

When the police are staking out Waingro's hotel room, they use a camera on their hotel room door's peephole. After the fire alarm goes off, the door is opened and the display of the camera on the television in the room doesn't move in accordance to the movement of the door.

In the coffee shop, the man sitting behind Vincent Hanna variously has a wine glass, a coffee mug and a beer bottle in different shots.

The shootout begins near the plaza at the intersection of Flower and 5th streets. After Bosko is shot Hanna gives chase and the getaway car is seen speeding, passing the spot where the shootout begun. Once McCauley starts shooting through a windshield window, the same spot is seen being passed again. The car is then seen passing the intersection, but once the tires get blown the car is at the intersection again with the plaza just few steps away.

At the drive-in, when Michael is firing his shotgun at the white Dodge truck, we see bullet holes in the passenger door. When the truck stops after hitting the fence barrier, these holes are missing.

The blood that splatters on the window when Breedan is shot down in the car is already on the window in the shot of the outside of the car before he is shot.



Factual errors

In the final scene, the approach light system at LAX airport is shown turning on and off for individual aircraft as they approach to land. In actuality, approach lights to runways remain lit at the same level of intensity for aircraft. They are not turned 'up' and 'down' for each airplane.

When Hanna's stepdaughter attempted suicide, she cut two arteries, the most important of which was her femoral artery in her leg cut at an angle which would prevented the artery from closing off. Plus, she was in water so the blood would not have had a chance to coagulate. She definitely would have bled out within three to five minutes.

When the news reporter is sharing the story about the robbery, it is stated that "A bank robbery that spilled into the streets took place in a small southland neighborhood." The shooting actually takes place in downtown Los Angeles. Mike tells the police to set up roadblocks at intersections of Flower as well as Figueroa. These are streets in downtown Los Angeles.

McCauley refers to a harbor-area bridge as the "Saint Vincent Thomas Bridge." It wasn't named for a saint, but for a California assemblyman named Vincent Thomas.

Eady listens to an announcer citing Kandinsky's Theory of Color. Goethe wrote The Theory of Color. Kandinsky wrote "?ber das Geistige in der Kunst" or Concerning the Spiritual in Art.



Incorrectly regarded as goofs

Drucker didn't need Charlene to identify her husband, Chris Shiherlis, he was only intimidating her into thinking she would be prosecuted for being an accessory and be separated from their son, he was also using her to trap Chris.

Neal approaches Breedan in the coffee shop and asks him if he would be willing to be the driver of the getaway car for a bank robbery that day. Even though Breedan accepts the offer without even asking how much money he would making, it's possible he already knows it's going to be a large amount because he knows Neal well enough to know he wouldn't take jobs with low payouts.

McCauley and his crew time the armored car robbery at the beginning of the film. As Hanna points out, it is because they know the LAPD response time to a 211 (armed robbery) is three minutes. While this, in practice, depends on factors such units available, their location, traffic conditions, and more, what they are talking about is the requirement that the police respond in no more than three minutes. Sure, the crew could get unlucky and have a police car just around the corner, but that is not the same as the coordinated response that then arrives. For stray responders that trickle in, the crew is prepared, standing in a perimeter guard around the armored car to take them on. If Donald knew and felt the restaurant manager was performing illegal and unfair labor practices he should have informed his parole officer. The manager lets Donald know that the parole officer is in on it.

At 1:35 Drucker says Chris doesn't talk to Charlene about their scores, therefore she wouldn't be charged as an accessory when he tells her she would be if she didn't help them apprehend Chris at 2:04. However, Drucker probably used threats of criminal charges and losing her son to scare Charlene into trapping Chris, since she has no legal background to know any differently. As Drucker states, Charlene was also in the foster system so she'd want to protect Dominick from what she experienced.



Revealing mistakes

When Neil shoots Van Zant, you can clearly see the wire running up his pant leg to trigger the squibs used to simulate gunshot wounds.

When Vincent is tailing Neil on the highway, he is holding down the microphone key of his walkie-talkie even when he is listening to other members of the surveillance team.

At the beginning of the sequence where Hanna drives up to a light, stops his car, and throws out his TV set, two extras on the left sidewalk can be seen waiting for the 'action' cue before they start walking.

When Vincent in Air 18 contacts JJ in Air 40 wanting to know the whereabouts of Neil, JJ says Neil is "on the 105 heading east towards the 110 interchange." After Vincent gets into the car on the Vermont on-ramp, they pass-through signs above the freeway clearly indicate they are traveling west on Highway 105, not east.

At the drive-in, when Neil backs up his car and crushes the gunman's legs, you can see the big metallic block on the ground used to protect the stunt man's leg.



Miscellaneous

At the climax of the film, Neil is hiding behind a box and Vincent is in the open. The plane is coming from behind Vincent, lighting him up, which means his shadow would be toward Neil. However, the scene shows Vincent noticing a shadow as if the plane's lights were behind Neil, Vincent turns and fires, hitting Neil. Neil would have seen Vincent in the plane's lights and should have had the first opportunity to shoot.

During the street shootout after the bank robbery, Breedan the getaway driver is shot and killed while driving. However, when the angle changes to show the car speeding down the highway, the brakes are applied hard just before hitting another car, even though the dead driver couldn't have applied the brakes.



Audio/visual unsynchronised

During the scene in which Albert tells Vincent about meeting his brother, Albert says, "Vincent, Vincent, I swear man, tonight's the best I can do for you." His mouth clearly does not match what he says.

When Chris and McCauley are having coffee in McCauley's living room, we see smoke rise and appear on the screen before we hear the sound of Chris' cigarette being lit.

When Chris first fires his weapon at the white pickup at the drive-in, the sound is that of one shot being fired, yet the instant the impact is shown on the pickup's windshield, there are two bullet holes.



Crew or equipment visible

A few crew members are reflected in the glass when Neil walks in front of Van Zant's house.

Camera and crew reflected in the balcony window when Hanna is in his hotel room.

A few crew members and their equipment are visible in the rear view mirror of Van Zant's delivery man's jeep at the drive-in.

The Steadicam operator's legs are reflected in the car doors following Chris's movement when he runs by a green car during the shootout.

A camera operator wearing a white hat is reflected in the getaway car's door at the bank.



Plot holes

In the final scene, Neil's action doesn't make much sense. As Hanna was out in the open, and Neil was hiding behind a container, Neil could easily get Hanna by looking and shooting around the corner. Instead Neil abandoned his cover, jumped out to the open, and acted like he's suicidal. That doesn't fit the character's instinct and principle of survival.

Police should be able to identify Shiherlis at the traffic stop outside Charlene's apartment. The police had Shiherlis under surveillance and would have distributed photos with an All-Points Bulletin to officers when trying to capture him, the officers at the traffic stop should have had photos and description (height, build, hair and eye color, etc.).

Chris Sherhalis would have known or suspected that his escape plan was compromised especially after the shootout following the bank robbery. That he didn't try to call his wife in advance before coming over to pick her up or that he would have driven into what could have been a trap is improbable.



Character error

During the night-time bullion-heist surveillance, Vincent and his men repeatedly begin talking on their handheld radios before pressing their transmit buttons. By doing so, they would cut off the first several words of each transmission.

McCauley is proficient enough in the combat use of firearms to do brass checks (e.g. when he prepares to shoot Waingro). Yet when Hanna stops him and asks him if he'd join him for a cup of coffee, he hides a cocked SIG P 22x-series pistol between himself and his car seat. Only someone completely unfamiliar with this sidearm would do this, as it is very unsafe (the gun's only external safety is a de-cocking lever and cocked, it has a very light and short trigger pull).