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: 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.
Character mistake: When Frank Serpico is recording his phone call regarding being transferred, the guy, who says the precinct is clean as a houndstooth, calls him Mike.
Audio problem: When Sepico and Lombardo are in the chief of police's office, when the camera shows the wide shot with the chief looking out of the window, you can hear Lombardo talking but his lips are not moving. (01:47:00 - 01:48:00)
