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.
Audio problem: When Buddy is in Sal & Angie's asking Angie Boca to model for him, their lips rarely match their words. Sometimes they appear to be saying something else, and other times it looks like they aren't speaking at all. (00:24:25)
Answer: The parking laws in the 1970's were not as strict as they are today, leaving a car on the street is no different from parking on the curb in a suburban area. The car was supposed to be picked up by the mob.