8 of the most revealing moments from Netflix's Sylvester Stallone documentary 'Sly'

While trying to find his way as an actor in New York City in the early 1970s, Stallone and his friend John Herzfeld constantly wrote scripts and talked about movies. They also snuck into theaters to watch movies throughout Manhattan.

After getting cast in the 1974 movie "The Lords of Flatbush" opposite Henry Winkler, Stallone took his $1,300 paycheck and used it to buy a $40 car, which he drove to Los Angeles.

It took him 11 days to get there. But right after he showed up in Hollywood, the car broke down. Stallone called Winkler, the only person he knew in town, and the actor picked him up, threw Stallone's giant dog and all of his clothes into his car, and dropped him off at a nearby motel.

After a few days, Stallone found a "dump" in the Valley to live in. "One street away from Balboa Blvd.," Stallone said.

After a while in LA grinding through audition after audition, Stallone got frustrated and began writing more, hoping that by writing material for himself, he could land acting work quicker.

Inspired by Martin Scorsese's "Mean Streets," he began writing a gritty story that followed a character named Rocky. But he was too unlikable in the first few drafts, so he reworked the character to have a softer side and a girlfriend. Stallone also turned Rocky into a boxer. 

Suddenly, things began to click. Producers liked the script and wanted to cast well-known actors like Ryan O'Neal or Burt Reynolds in the role.

However, Stallone was adamant that he wanted to play Rocky.

Stallone said he was getting offered more and more money to give away the rights and the role. Archival footage in the documentary shows Stallone in a TV interview saying that it got up to $265,000 for him to walk away, but he knew if he ever agreed he'd be bitter the rest of his life that he "sold out."

In the documentary, Stallone said that Ken Norton, a legendary pro heavyweight boxer who fought the likes of Muhammad Ali and Larry Holmes throughout his career, was originally supposed to be the brash Apollo Creed.

But he dropped out two days before filming started, so the role went to Weathers. 

After "Rocky" was released in 1976, won best picture at the Oscars, spawned a franchise, and turned Stallone into an instant star, the actor embarked on making an action movie with 1982's "Rambo: First Blood."

To take on the role, he began researching Vietnam War veterans and used a collection of stories to form the foundation of John Rambo.

One such story of a soldier recounting watching his friend's legs getting blown off during the war sparked Rambo's hysterical soliloquy at the end of the movie, which wasn't originally in the script.

However, it was written down that Colonel Trautman, a superior of Rambo's, was supposed to kill him at the close of the movie in a slow-motion shot.

"I said to the director, this is not good." Stallone said in the documentary. "I don't want everyone who is a Vietnam vet to see this film and me shot and realize, oh, so there's no hope for me at all. None."

Stallone said the ending in which Rambo dies scored awfully at a test screening, so they scrapped the scene and had Rambo arrested at the end of the movie instead. 

In 2019's "Rambo: Last Blood," the movie concludes with a badly wounded John Rambo walking to the front porch of his father's house and sitting on a rocking chair.

Originally, Rambo was supposed to die in peace in the final shot as the camera pulls back and the rocking chair stops rocking.

But during post-production, Stallone had second thoughts.

Not wanting to see Rambo go out like that, he had the shot digitally altered so it looked like the rocking chair was still rocking throughout the shot.

"I so believe we don't see our heroes die before our eyes," Stallone said in the documentary. "That there's always some mystical quality about them."

In the 1990s, Stallone's stardom grew from the success of the "Rocky" and "Rambo" franchises, but also because of his rivalry with fellow action star Arnold Schwarzenegger.

The competition wasn't just limited to how big they looked on-screen or whose movie had the biggest explosions, though. They also went after the same roles — which led to one box-office disaster for Stallone. 

A script for an action comedy titled "Stop! Or My Mom Will Shoot" began making the rounds. It was offered to both actors, and though Schwarzenegger wasn't into it, he admitted in the documentary that he didn't let his lack of interest show. Rather, he pretended to be into it to lure in his rival.

Finally, Stallone landed the movie, thinking he one-up'd Schwarzenegger. But Schwarzenegger got the last laugh.

Released in 1992, "Stop! Or My Mom Will Shoot" was lambasted by critics and is considered one of the worst movies Stallone has ever made.

In 1997, Stallone was cast in the drama "Cop Land" opposite the likes of Harvey Keitel, Ray Liotta, and Robert De Niro.

In one famous scene, Freddy Heflin (Stallone) walks into Moe Tilden's (De Niro) office looking for some help, but he doesn't get it. Instead, Moe fires back at Freddy, "I offered you a chance to be a cop, and you blew it!"

Stallone revealed in the documentary that the line wasn't in the original script. Initially, Moe was supposed to say his "hands are tied" with Freddy walking out, disgusted. Stallone wanted to get more out of De Niro, though. 

"I really wanted him to hit me as hard as I need to be hit for me to feel as though I'm playing the character properly," Stallone recalled. "I need to walk out of this room demolished."

He said he tried to get under De Niro's skin. Instead of just walking out of the office, Stallone instead went off the page and kept insisting that Moe needed to help him.

Finally, De Niro got so enraged that he delivered the famous line.

"Thank you, Bobby," Stallone said with satisfaction in the documentary.

Stallone said his father was "physical" toward him and his older brother Frank while growing up. Stallone said he based a lot of his Rocky and Rambo characters on his dad's traits. 

His father, who died in 2011, was also so jealous of his son following the success of "Rocky" that he wrote his own script.

The rivalry hit its peak when the duo played against each other in a polo match.

As a kid, Stallone was a great polo player because of his father's love of the game and horses.

Once a big star, Stallone put together a big polo match. During the match, his father rammed his horse into his son's, causing Stallone to fall off and injure himself.

"He just rode away," Stallone recalled about his father's reaction. "That was it, I never played polo again from that moment on. I sold everything, every horse, ranch, truck, and that was an end."