The original Rocky's shoestring budget forced director John G. Avildsen to cut a number of corners, perhaps most notably during the scenes showing Rocky jogging through the streets of Philadelphia. More often than not, the crew was operating without permits or hired extras, using only the bare minimum of equipment so they could get on and off the shoot without attracting attention. The scene of Rocky running past a boat moored along the docks was a spur-of-the-moment decision from Avildsen, who made the shot himself after having Stallone get out of the car and run alongside it while they were out scouting locations. The part where Rocky's loan shark boss pulls out an inhaler and puffs on it mid-convo? You guessed it—unscripted as well.

The greatest unscripted scene in Rocky, and arguably the entire franchise, takes place when the Italian Stallion erupts in frustration after Mickey Goldmill (Burgess Meredith) offers to manage him. Rocky's monologue during this scene was entirely improvised by Stallone, who later admitted that when he yelled "this whole place stinks," he wasn't acting—the apartment where they were filming really was cursed with a rotten odor.