Arnold Schwarzenegger admitted that he had made up several stories in the movie for attention because the producers told him that without drama it would be boring. One of the stories made up was the fact that he did not attend his father's funeral because of a body building competition that was going to happen in a couple of months. Arnold did actually attend his father's funeral and spoke to him shortly before he passed.
More than 100 hours of footage was filmed. It eventually had to be edited down to 85 minutes, however, on the 25th anniversary DVD more footage was shown.
The 1975 IFBB Mr. Universe/Mr. Olympia competition took place in Pretoria South Africa during the height of apartheid. Before the event could even take place, an apartheid neutral venue and lodging accommodations had to be found as there were several black bodybuilders competing who wouldn't have been allowed to compete on the same stage with or even stay in the same hotel or even sit at the same table to dine with their white counterparts.
To give the film a narrative arc, and thus mainstream appeal, the film was originally meant to follow actor Bud Cort being trained by Arnold Schwarzenegger over a year, using his physical development to explore the principles and world of bodybuilding. Cort and Schwarzenegger recorded several hours of footage but ultimately felt he was wrong for the project and amicably parted ways with the production; he forfeited his salary, asking that it go towards the budget of the film. Some of his footage eventually appeared in Raw Iron: The Making of 'Pumping Iron' (2002).
The term "pumping iron" was coined by bodybuilder-author Charles Gaines to encapsulate the art of weight-lifting.