After Coffee Cakes is brought to the bathroom, in one of the next shots you can still see that Coffee Cake's body from the waist down is still visible. In the left of the frame is his body and to the right is the brick wall. The clothing that Coffee Cakes is wearing gives it away that it is him.
The Beatles' "Come Together" is playing in Sonny's bar just before and during the "biker" scene. This song would not have been available on a jukebox, radio or anywhere else in 1968. It was not recorded until July 1969, and was not released until the fall of 1969.
When the detectives are first bringing Colagero 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.
Early in the movie, when we first see Calogero on the bus, he's wearing a white dress shirt. When Lorenzo drops him off at their bldg, Calogero is wearing a white T-shirt as he looks up at his Mom. After we see his Mom in the window waving, he has the dress shirt on again.
When Sonny is telling Eddie Mush to be put into the bathroom, Calogero's head can be seen right next to Sonny, but in the next shot (which shows the whole room) when Mush is being pushed away, Calogero is nowhere to be seen.
After Lorenzo gives Sony the money back and leaves the bar and Calogero asks where his money is Lorenzo hits Calogero, the voice over of "C" says that was the last time his father spoke to Sony, the last time Lorenzo speaks to Sony it is after "C" returns the car and then Sony slaps "C" and Lorenzo confronts Sony about why he hit his son
When Phil give Calogero the peaches it's daylight. He goes upstairs & he's confronted by his parents about the money he got from Sonny. They go to the bar to give the money back and it's dusk. They give the money back to Sonny and leave the bar, and it's now dark.
When Lorenzo comes outside his apartment building with young Calogero to give Sonny back the money, it's daylight. When he's walking into the bar (2 doors away), it's beginning to turn dark, and when he walks out of the bar 2 minutes later, it's nighttime.
C's voice over at the start of the Aqueduct racing scene states that the Yankees were in last place in 1968. The Yankees were actually in 5th place out of the 10 American League teams of that year. It wasn't until the following year that the AL split into divisions.
At the beginning of the movie during the opening credits, there is a shot of the front of the bus. Behind the bus, there is a silver car that is clearly not from the 50's era. Possibly a late 80's or early 90's car.