Factual error: It's supposed to be 1960 but the parking meters on the street where "C" lives are the new kind with the slits for coins rather than the slots. These parking meters did not exist until 1973.
Factual error: When the detectives are first bringing Calogero out to the street after the shooting by Sonny, an electronic siren can be heard winding down and cutting off mid-tone. Only motor-driven sirens were available on emergency vehicles during this period, and when they were turned off, they simply wound down.
Factual error: The red and black destination signs shown on the GM old-look busses during the 1960 scenes weren't used until the late-'70s. The early signs were simply black and white.
Factual error: Although the movie neighborhood is meant to be 187th Street and Belmont Avenue, a NYC bus (from the old Surface Transportation System) is shown running along that street, where none ever did. In at least one scene, the sign on the bus indicates it's the 12 bus, Fordham Road from Sedgwick Avenue to City Island. Fordham Road was three blocks north of 187th Street, and never had its own bus route.
Factual error: A scene in front of Aqueduct Racetrack shows a fire hydrant with security caps that weren't invented until the mid '80s, approximately 17 years after the film is set.
Factual error: The traffic lights back then were dark brown decorative posts with only a red and green light, and they were firmly attached to the sidewalk. The ones in the movie came much later (but before 1993, obviously).