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.
Audio problem: As Popeye and Detective Russo are in the bar staking out Sal Boca, each have drinks. As they raise the glasses to their mouths, the sound of clinking ice cubes is heard. When Popeye downs his drink, the ice clinking is again heard, even though there is actually no ice in his glass.