Continuity mistake: Gator's brown Ford sedan alternately does and doesn't have rear bumper guards during the first moonshine chase. (00:40:10)
Visible crew/equipment: Denise arrives at her flat and finds the OAS Member there, with his back to the camera. To his right in the mirror the right half of director Fred Zinnemann's body and forearm is visible for a split second. (00:20:40)
Visible crew/equipment: The morning after the bar shooting, when Charlie and Johnny Boy are in the apartment, we can see the outlines of the hidden mic wires at the front of both of their undershirts, as well as the bulge of the mic transmitter at the back of Johnny's waist. (00:50:35)
Continuity mistake: In the scene where Serpico is in his apartment speaking to his girlfriend explaining how hard it's been to be an honest cop, he is drinking what appears to be a full glass of white wine. In the following shot of the both of them, Serpico sets up two unused glasses, opens a bottle of wine and pours it into the two glasses. His original full glass of wine is nowhere to be seen.
Continuity mistake: Talking with his new and still wet behind the ears boss, Rizzo advises him against trying to blitz the one-handed delinquent. He is making a gesture with his right hand, but at the cut here he is moving his left hand instead, with the arm that suddenly is on the table. (00:27:15)
Continuity mistake: When Howie is having his supper, watch how his grip on the beer glass changes from three fingers on the front of the glass, to holding the handle with all his fingers when he asks Willow for an apple and she replies "No apples" (00:21:00)
Continuity mistake: The truck from "Dupont" arrived in Paris and the human content can get off. There is one view from inside the building; look at the extra with a reddish sweater. He is inside, but also a few seconds later he is one of those people who still have to walk the path between truck and door with Shaft. (01:28:45)
Revealing mistake: There is a scene where a prisoner is executed by guillotine. Just as the blade would hit the man's neck, the view/scene changes slightly. The dummy used for the man's head can be seen.