Continuity: When the drug tester gets done with testing the heroin, he blows out the lit candle on the bottom. But when there is a far shot of him talking, the candle is still burning.

Continuity: During the car chase scene under the "B" Elevated Train in Brooklyn (86th St.), Gene Hackman passes the same curve at least 3 or 4 times. Look closely, you'll probably see the same movie theatre over and over again. Apparently, they rerun the same chase clip to increase the length of this scene.

Plot hole: When the police investigate the car in which they suspect drugs are being hidden, they really tear it apart - they rip out linings, pull apart fittings, pry off bits and pieces, etc. However, when, after a short period of time, it is returned to the actor who brought it in, he does not notice that it has been tampered with. It really would have taken a much longer time and a lot of the right fittings and materials to put it back together again in such good condition.

Continuity: When Charnier is still in France, he takes a gift to his girlfriend. She goes inside, and he picks up a fishing pole. He turns, and she comes back outside. The pole is gone. There was no indication he put it down or dropped it over the wall.

Continuity: During the car crash scene, the Commanding Officer, Hackman, Scheider and the other cop are walking toward the accident. Close shot of Hackman, as he says: "I say we keep sitting on Boca", they all stop walking. Immediate cut to long shot, and they are all still walking toward the accident.

Continuity: During the subway chase scene, Gene Hackman's car loses about a half dozen hubcaps! The hubcaps are back in place when Hackman parks the car at the end of the chase.

Factual error: The "B" train which he is chasing normally runs on the right most track (there are 3 tracks on this particular line). The middle one is never used except for out of service trains. Most of the train stations on that line service the right or left track, not the middle one.

Continuity: When Popeye's being shot at by the sniper, he's hiding behind a tree and rolls towards a wall that's relatively well-lit by sunshine. The angle changes and it's now completely in shadow.

Continuity: At the beginning of the film in Brooklyn, it is obviously dark outside (nighttime). As they are chasing the guy from the bar, it all of a sudden is during the daytime as it is light outside.

Factual error: Check out the sign over the front of the train, it should read "B", not "N". The "N" train runs on an entirely different line.

Audio problem: As Popeye Doyle is chasing the elevated train, he is continually honking his car's horn to warn pedestrians and whoever else to get out of his way. One scene shows him with one hand firmly on the wheel, and he hits the top-most rim of the wheel in frustration, and the horn honks on both hits. That car did not have a rim-blow type horn mechanism - only Fords had those, and this was a Pontiac Le Mans.

Continuity: At the start of the movie in France, we see an undercover French policeman shot by Pierre Nicoli, if you look quickly when the policeman is shot, we can see blood splatter all over his face. However, when we see the wider shot of him falling down his face is clean and has no blood on it at all.

Audio problem: As Gene Hackman and Roy Scheider are in the bar staking out Tony Lo Bianco, they are each drinking mixed drinks. As they raise the glasses to their mouths, the sound of clinking ice cubes is heard. When Hackman drinks his drink, the ice clinking is again heard, even though there is no ice in his drink.