The Stunt Man

Cameron (Steve Railsback) is a young veteran running from the police. He stumbles onto the set of a World War I movie and isn't sure if he has accidentally caused the death of one of the film's stunt men. The eccentric and autocratic director, Eli Cross (Peter O'Toole), agrees to hide Cameron from the police if he will take the dead man's place. Cameron soon begins to suspect that Cross is putting him in excessive danger. At a bar one night, another member of the production gets drunk and tells Cameron that Eli almost killed the helicopter pilot during the fatal accident Cameron caused, because he insisted he keep flying in order to get the shot. Cameron falls in love with Nina Franklin (Barbara Hershey), the film's star, and is devastated to find out that she and Eli slept together before he met her.
The boundaries between reality and fiction become increasingly blurred as Cross exercises godlike control over the production. During a screening of some footage for Nina's parents who are visiting the production, a nude sex scene with Nina is shown. Eli appears to be mortified, but allows the footage to play anyway. He waits until Nina is just about to shoot a traumatic scene the next day to tell her that her parents have seen the footage of her naked. It causes her to cry with humiliation, which seems to be the exact emotion Eli needs from her in the scene.
The final day of filming involves a complicated stunt where Cameron has to drive a vintage Duesenberg off a bridge. Nina has two other scenes to shoot as well, but Cameron is convinced Eli will rig the stunt so he will die. He persuades Nina to run away with him, but they are unable to leave the set, which is kept sealed from the neighboring town by the police on Eli's orders. Nina hides in the trunk of the Duesenberg, promising to slip away with Cameron during the stunt.
Before the scene is shot, Eli points to the Duesenberg and explains it is the only copy of the vintage car that the production has. He therefore orders that no one interrupt the filming of the scene once it begins. Cameron is beside himself with anxiety. He keeps trying to check the trunk to see if Nina is there, but finally decides that he will find out once he has escaped in the car. When he gets behind the wheel, the police chief asks if the in-car camera is on. Cameron mishears the question "Camera on?" the stunt man starts the car and speeds away before anyone is expecting it. The entire crew springs into action. Eli screams at them to start shooting.
Cameron thinks he has escaped when he arrives at the bridge. He flips off the camera, but a crew member triggers a charge which causes a blowout in a front tire. The car swerves off the side of the bridge and into the water. As it sinks, Cameron climbs into the back seat to free Nina from the trunk. Then he sees her standing next to Eli on the bridge, looking down on him. He swims to the bank. Eli descends behind him on a crane, and helps Cameron come to the realization his life was never in danger. Cameron says that the stunt is the hardest $1,000 he has ever made. Eli corrects Cameron, saying the pay for the stunt is only $650. Cameron becomes enraged, insisting he was promised $1,000. Eli laughs at him and offers to split the difference at $750. He flies off in the helicopter, leaving Cameron screaming at him.

Question: What do the boundaries between reality and fiction become in this movie?
Answer: Blurred