No machine guns were mentioned in this part of the novel. The novel refers simply to guns which were probably just hand guns. The use of more assassins in the novel and of machine guns in the movie was for dramatic effect. Using so many machine guns in such close quarters would have endangered all the trigger men.

A causeway is the term that applies to a roadway over a body of water as opposed to a bridge.

I allways thought that the car with Sonny's bodyguards in it should have arrived at the tollbooth alot sooner than it did. I didn't think Sonny got that much of a head start on them and that he would have outpaced them for that much distance.