Visible crew/equipment: Towards the end of the film when Billy runs at the top of the screen towards the exit of the jail, you can see the film crew at the bottom of the screen.
Visible crew/equipment: When Billy bribes the main guard, who then drags him up to his office, the camera pulls back dramatically to reveal a crew member tracking them with a boom mic.
Visible crew/equipment: When Billy's girlfriend, Susan, visits him at the insane asylum section of the prison, just before Susan enters there is a reflection of a crew member on the left side of the screen giving the shot a ghostlike image. (01:35:15)
Visible crew/equipment: Billy is going crazy, kicking a guy on the ground. The camera follows the action. In one scene the shadow of the operator is blatant on the left side. (01:37:00)
Visible crew/equipment: Billy runs into a bus, narrowly missing a door closing. He looks out the window and smiles. The head of a crew member is visible reflected in the glass.
Revealing mistake: Watch carefully during the fight scene between Billy and Rifki, you can see the stuntmen a few times.
Answer: Max WAS a real character, and a Dutchman in real life, rather than an English one as portrayed in the movie. He eventually got paroled and later treatment for a severe drug addiction he had too.