Francis Ford Coppola contributed money to the budget of the film. However, it is rumored that he lent Martin Scorsese $3000 as the Mafia shook him down for using the San Genaro Festival as a backdrop without "permission". It's generally presumed he Mafia uses the all-cash festival to launder money from their ill-gotten gains.
To really get inside Harvey Keitel's drunken scene, the camera was actually strapped to the actor while he swayed about, and under-cranked to give it a woozy, drunken feel.
The innovative use of the hand-held camera was largely down to the fact that the film's meager budget didn't stretch to laying down lots of tracks for all the tracking shots.
The title change from "Season of the Witch" was inspired by a quote from Raymond Chandler: "Down these mean streets a man must go." Film critic Jay Cocks suggested the change to Martin Scorsese, who thought it pretentious at first but eventually came to agree that it was effective.
Clearing the songs for use in the film ended up being approximately half of its budget.
Martin Scorsese: as Jimmy Shorts. Additionally, he appears another two times. First, he is visible in a "portrait" with Harvey Keitel (for one frame) in the opening home movies and main title sequence. Second, his voice appears as narration: "Father, I'm not worthy of your flesh."