Joe Spinell, who played the title character in William Lustig's Maniac, was cast in the small role of the corrupt lawyer Eisenberg. During the filming of the courtroom scene, Lustig recalled that Spinell's escalating alcohol and drug abuse was becoming a problem as Spinell would often show up late for filming and often drunk or stoned or both which slowed production. One morning, Spinell did not show up at all which led Lustig to shut down filming for half the day while his producer partner, Andrew Garroni, had to go looking for Spinell on the streets from various bars to hotels where he might be. The scene where Eisenberg arrives late in the courtroom after speaking with Prago was filmed in late afternoon on that day that Spinell did not show up that morning for filming.
The scene after Frank Pesce is being beat up in the bathroom by Richard Bright and Joe Carberry, Fred Williamson picks him up and puts him out the window was done with no safety nets or wires with Williamson holding onto him really tight.
Sandy Alexander who plays the prisoner who harasses Robert Forster in the film was in fact was the leader of the New York Hell's Angels unbeknown st to director William Lustig and after the film was released, Alexander was convicted of murder.
The scene where Willie Colon is killed by Robert Forster, the actress that played Colon's girlfriend was jerked so hard backwards that the cast and crew worried for her safety after landing hard in the bathtub. This was a complete accident and she was a "trooper" according to William Lustig
The chase scene where Fred Williamson chases Frank Pesce was shot in a public swimming pool in Brooklyn which took about 40 different set ups to accomplish.