When Vincent Coll was killed, he was using a phone booth in the London Chemists drug store at Eighth Avenue and 23rd Street. He was reportedly talking to Owney Madden, who kept Coll on the line while the call could be traced. Soon enough, a limousine pulled up outside. While Bo Weinberg waited behind the wheel, Leonard Scarnici and Anthony Fabrizzo stepped out. One of them waited outside and the other walked inside. After telling the cashier to "Keep cool, now", the killer withdrew a Thompson submachine gun from under his overcoat and went back to the phone booth where Coll was. The gunman opened fire, raking up one side of the glass booth and down the other. A total of fifteen bullets were dug out of Vincent Coll's body at the morgue; even more may have passed clean through him. The killers were chased unsuccessfully up Eighth Avenue by a detective squad that had pulled up just after Coll was killed. (For some reason, the film instead shows the police trapping and killing Coll in the phone booth after he fires at them with a Tommy Gun.)
In the film, Coll accidentally shoots children as he's trying to escape an attack. In reality, Coll unsuccessfully attempted to kidnap Joey Rao, a Schultz underling. The resulting shootout left a five-year-old child, Michael Vengali, dead and several children wounded.
Vincent Coll was born in Ireland and spoke with an Irish accent. In the film there is no mention of Coll ever living in Ireland and he has no accent.
At the end of the film, Mad Dog Coll is seen wearing a wig as a disguise. The real Mad Dog Coll dyed his blonde hair black.
After the impromptu violin concert, Coll puts the Thompson gun into the violin case with the drum magazine still attached. It is far too big to fit in the case, but there's a jump cut to him shutting the lid. It happens fast and it's easy to miss.
Set in the 1930s the shootout scene on the dock by the river has late model cars (from the early '60s when the movie was made) driving on the overpass in the background.