After producers Irwin Winkler and Robert Chartoff became interested in the script, they offered Sylvester Stallone an unprecedented $350,000 for the rights. He had $106 in the bank and no car, and was trying to sell his dog because he couldn't afford to feed him, but he refused to sell unless they agreed to allow him to star in the film. They agreed, on the condition that Stallone continue to work as a writer without a fee, and that he works as an actor for scale. After Winkler and Chartoff purchased the film, they took it to United Artists, who envisioned a budget of $2 million with an established star, particularly Robert Redford, Ryan O'Neal, Burt Reynolds, Nick Nolte or James Caan. When Winkler and Chartoff told United Artists that they could only get the screenplay if Stallone starred, United Artists cut the budget to $1 million and had Chartoff and Winkler sign agreements that they would be personally liable if the film went over budget. The final cost was $1.1 million. Chartoff and Winkler mortgaged their houses for the last $100,000.

After the end of filming, Stallone kept the two turtles "Cuff" and "Link", and as of June 2019 he still had them, alive and well.

Rocky's dog Butkus was Sylvester Stallone's real-life dog.

Most of the scenes of Rocky jogging through Philadelphia were shot guerrilla-style, with no permits, no equipment, and no extras. The shot where he runs past the moored boat for example, the crew was simply driving by the docks, and John G. Avildsen saw the boat, and thought it would make a good visual, so he had Sylvester Stallone simply get out of the van and run along the quays, while Avildsen himself filmed from the side door. A similar story concerns the famous shot of Rocky jogging through the food market. As he runs, the stall keepers and the people on the sidewalks can clearly be seen looking at him in bemusement. While this works in the context of the film to suggest they're looking at Rocky, in reality, they had no idea why this man was running up and down the road being filmed from a van. During this scene, the famous shot where the stall owner throws Rocky an orange was completely improvised by the stall owner, who had no idea that a movie was being filmed and that he would be in it.

Sylvester Stallone insisted that the scene where he admits his fears and doubts to Adrian the night before the fight is to be filmed, even though production was running far behind and the producers wanted to skip it. Stallone had only one take for the scene, even though he considered it to be the most important scene in the film.

Continuity

During the big fight, the arena is clearly empty at times. This is because only 50 extras could be afforded for the scenes, and despite cinematographer James Crabe's best efforts to hide this fact, occasionally, if one looks hard enough, one can see most of the arena is empty.

The number "2" disappears off Rocky's apartment door after he answers the door to let Micky in.

At the end of the fight, when Apollo and Rocky are hugging, Apollo's manager comes up to him in the close-up shot. Then they switch to an aerial shot, and Apollo's manager jumps over the ropes into the ring.

When Rocky enters the bathroom while Mickey is visiting him, three darts are on the door. After Rocky opens the door the first time, the darts are in a completely different pattern. In the final shot, the door has 2 darts.

In the final fight, just before we see the sign for Round 13, there is a shot of Rocky in a clinch looking fairly unmarked even though the previous rounds had shown him already very bloodied.



Factual errors

When Rocky first runs up the Art Museum steps, there's a shot of a Daily News delivery truck near City Hall. A bundle of newspapers gets tossed out the back and the truck pulls away as the back door is pulled down. Not possible as these trucks were manned by only one person.

For a film shot in Philadelphia, and whose main characters were supposed to be born and bred Philadelphians, Rocky, Paulie, Gazzo, and Mike all spoke with a "Movie Brooklynese" accent. The only person with an authentic "Philly Accent" was the character, Marie, the young girl in front of The Atomic Hogie Shop.

After Rocky's fight against Spider Rico, his payment is winner's share: $65, less $15 for use of locker and corner man, $5 for use of shower and towel, and 7% tax. In the end, he gets a total of $40.55. However, 7% of $65 is $4.55, so subtracting that and the other deductions; he actually should have received $40.45, not $40.55. Spider Rico did receive the correct amount.

Empty seats are visible in close ups of the 2 boxers.

South paw is a baseball term not a boxing term. It's a left handed pitcher because, when built correctly, center field should be on the east side so the batter isn't looking at a setting sun. Therefore first base is south, the direction a left handed pitcher would be facing while in the stretch.



Revealing mistakes

After the announcer finishes announcing the beginning of the fight, the microphone rises back up to the ceiling. As it rises, it hits the camera and shakes it.

When Rocky is demonstrating his training technique for the news story, the camera angle on Rocky changes multiple times but there was only one camera present.

When Adrian and Rocky leave for their date, there is a rose bush in front of the house that has two fresh roses on it and some flowers on the ground in bloom. Since it is late November in Philadelphia and it is obviously cold, this wouldn't be possible.

During the fight against Apollo, when Rocky gets his eyelid cut open, if you look closely, the man cutting it is actually squeezing a tube of fake blood onto Rocky's eye.

During the big fight scene, the police officers on duty are clearly Los Angeles Police Department members (as the scene was shot in LA), not Philadelphia Police Department members.



Miscellaneous

Rocky fights Apollo at the Spectrum Stadium in Philadelphia. As Adrian comes out to watch the fight, a Los Angeles police officer is standing behind her in the corridor.

The closing credits list real-life boxing referee Lou Fillipo, who plays the referee in the Championship fight, as "Championship Fight Announcer". Thayer David, who plays the promoter Jergens, was the fight announcer.

It was said by someone that flowers wouldn't be blooming that late in November (Thanksgiving), but in reality there are several varieties of roses and flowers that bloom all the way through December. It is very possible that the flowers in front of the house are Christmas Rose.

During the walking of Marie from the corner store to her home, you can hear the camera rolling.



Anachronisms

About a half hour into the film, Rocky is looking at pictures and clippings on the wall, and there is the sound of a steam locomotive coming up to speed, along with the sound of its steam whistle. Diesels had long since supplanted steam in Philadelphia and most of the country in 1976.

On the 2001 Special Edition DVD, the last half of the 1982 United Artists logo fanfare is heard on the 1976 logo. This is due to a plastering error.



Audio/visual unsynchronized

At the end of the fight Apollo say there ain't gonna be no rematch and then Rocky says "Don't want one", but his mouth is clearly closed.

During Paulie's drunken argument with Rocky and Adrian, he smashes the lampshade with a baseball bat and then just after that a further smashing sound can be heard before his baseball bat makes contact with anything.



Crew or equipment visible

When Rocky is talking to Adrian on Thanksgiving through the door, the camera shot goes to Paulie who is about ten feet away. You can see one of the movie cameras in the mirror.

During the fight, Steadicam operator Garrett Brown and his assistant are visible at ringside several times in the wide shots. Brown can clearly be seen wearing a black and white stripped top.

In the Morning Run scene, the camera zooms out as Rocky runs down the street. The lighting equipment is visible at the top of the screen, right above the farthest building.

Shots of the stedi-cam operator in striped shirt moving around the ring.

When the fight between Rocky and Apollo is shown on the bar's television, there are tracking lines visible on the bottom and center of the screen. These artifacts are only present on analog recordings and wouldn't appear on a live broadcast.



Errors in geography

In an early scene, Adrian and Rocky are talking on a street in "South Philadelphia" while an elevated train passes in the background. There are no elevated trains in South Philly.

Rocky wakes up at 4:30am to start his exercise regime, it is December. When we see him out jogging up the steps, the dawn is breaking. The sun should not be coming up until after 7:00am (Unless he ran for 2 & 1/2 hours!)



Plot holes

Incorrected regarded as goof. When Rocky knocks down Creed in the first round, he doesn't go to a neutral corner until a good 10 seconds after Creed hit the canvas. This was critical because the referee cannot start the count until the fighter is in a neutral corner. As it took Creed to the count of 8 seconds to get up off the canvas, had Rocky gone to a neutral corner immediately Creed would've been counted out and Rocky would've been champion via a 1st Round KO. 55 seconds into the first round, Rocky scores a knockdown and Apollo doesn't rise to his feet anywhere near the count of 10. If you count it out, it's more like 15-18, depending on how fast you count. Rocky wins in the first round.



Character error

When Rocky is boxing in the meat-packing plant, he is in an orthodox stance, not southpaw.

Apollo describes "January First... The country's biggest birthday..." July 4th is considered the country's birthday.

Mickey states he's been in this racket for 50 years. Yet he mentions a fight back from 1923, which makes us 52 years already and that wasn't even his first match, otherwise he would have mentioned it. It would be also difficult for guy like Mickey to downplay how long he's been in the boxing business, especially when he?s trying to convince Rocky that he needs a manager. He would rather be either accurate or exaggerate.