Continuity mistake: When Falfa's Chevy flips over, we can see that it has no fuel tank at all in it. However, in the next shot the car now has a visible fuel tank, and it explodes.
Continuity mistake: In the first scene where the truck drives along the road, if you look in the top right hand corner you can see the shadow of the helicopter that was filming the shot.
Continuity mistake: Motorcycles used by traffic officers throughout the movie are Moto Guzzi V7 850. In the scene on the docks, two officers arrive on Moto Guzzis, but the moment they ride up the narrow ramp, they suddenly ride Triumph Bonnevilles. The two Triumphs are slightly different. Trained eyes can tell that the traffic cop and Callahan use them interchangeably, switching back and forth a few times. (01:45:45 - 01:52:55)
Continuity mistake: In some of the locker room scenes, the overhead boom microphone is visible, and clearly shaking.
Continuity mistake: Close-up interior shots show that Gator's brown Ford has a Hurst floor-shifter and manual transmission. But when he arrives at his parent's home, he very obviously puts the column-mounted automatic shifter into 'Park'. (00:17:10)
Continuity mistake: During the fight scene with Oharra, Bruce Lee was actually cut quite badly on the hand. In later scenes in the film he can actually be seen with a bandage round the injured hand.
Continuity mistake: When Barbra Streisand meets Robert Redford on the street at the end of the film, the camera shoots her from behind and her coat collar is standing up. When the angle shifts to the front, her collar is neatly in place.
Continuity mistake: In the final scenes where Sheriff Pusser drives a police car to the Lucky Spot, just before he arrives, in the long shot of him driving down the highway, the patrol car has red lights on it's roof. When he arrives and drives the car through the bar, the car has blue lights.
Continuity mistake: In one scene the actress is wearing a tight fitting sweater which clearly shows that she is wearing a bra. In the next shot she stands up to say she is off to have a shower, whips off her top and - you've guessed it - no bra!
Continuity mistake: Near the end when Howie is in the cage and praying, one shot shifts to the line of watching islanders. Summerisle walks towards them, turns and signals with his left arm. Cut back to Howie in the cage, then back to the islanders. The same sequence of Summerisle walking and signalling is then shown again.
Continuity mistake: During the fight between A no 1,and Shack. Shack is cut with the ax, the ax head is coated with "blood," as A no 1 is setting up for another swing you can see the ax head behind his head, it is still "bloody," but as he starts the swing, the ax head is shiny and clean, and then it's bloody again.
Continuity mistake: Shortly before Sol's death, Thorn rushes into the suicide center and talks to him from the control room above. When Sol pleads Thorn to listen, there's interference on the intercom. Now watch the control panel: The earphone cable on the left side dangles back and forth each time the "speaking permitted" sign flashes on and off, blatantly revealing the cheap trick they used to make the display flashing - they simply toggled the "on" and "off" frames. (01:17:30)
Continuity mistake: In the scene where Eastwood is watching "the city of Lago volunteers" training,he is drinking a beer. The first time he lifts the glass to drink, it is about half empty. After he says something to the man with the knife, he lifts the glass for another drink and it is nearly full.
Continuity mistake: Trixie Delight's room number in the hotel is 235, but when Imogene and Addie go to Addie's hotel room, which is right next to Trixie's, the number on the door says 235, too.
Continuity mistake: As the blue sedan turns onto the street where the children are playing, the street is entirely in shade. But after the children begin reacting, the car approaches in full sunlight. (00:56:20)
Continuity mistake: In the scene where the inmate is being beheaded in the courtyard, as they change shots for the special effect you can now see that the sun has moved and is glaring into the camera lens and the executioner is now visible standing next to the guillotine.
Continuity mistake: During entire scene with dancing king Herod and his men, shadows on the floor are at different angles from one shot to another. (01:16:15 - 01:19:30)
Continuity mistake: When Serpico finds three black men raping a girl in the park, one of them cuts the girls face slightly and the cut is very visible. The camera then cuts away then back and the cut and blood is gone. (00:10:25)
Continuity mistake: There is a scene which is supposed to take place either on or about the day Kennedy was assassinated, where a boy is delivering newspapers. The newspapers have the infamous "Wanted for Treason" handbill wrapped around them. The handbill was distributed on the streets of Dallas and not as part of any newspaper.
Continuity mistake: Inspector Lebel's level of grey hair colour varies quite markedly back and forth during the movie.