Directors and producers never wanted Talia Shire to play Adrian because they felt she was too pretty to play a shy girl like her character. So she came to the interview dressed down and was awarded the part.

Adrian's hesitation to kiss Rocky in his apartment after their date together wasn't originally scripted that way; Talia Shire was suffering from the flu during filming, and she was afraid of getting Sylvester Stallone sick. What resulted ironically was a better acted scene than was originally anticipated.

Sylvester Stallone once stated on Conan O'Brien, that in one of the very earliest versions of "Rocky", the character had a strange kind of condition. If he didn't eat a banana every now and then, he'd fall into a coma.

The scene, where Sylvester Stallone tells Talia Shire that he cannot win the bout against Apollo, was originally ordered to be cut out and Stallone had to plead and beg to get it in the film. Finally they told him that he could try it once, but if he didn't get it done in one shooting it would be left out of the film. He was so terrified of messing up his one chance that he got himself drunk before he got in front of the cameras. You can hear it pretty from his voice, too.

Rocky's home neighborhood (where the gym and pet store are) are supposed to be in South Philadelphia. However, the pet store and vacant lot which posed as the gym are actually at the corner of Front and Susquehanna, in the Kensington section of Philly. The same mistake is made in Rocky 2 and 5.

Sylvester Stallone made a mere $23,000 for writing and starring in the film.

Due to budget constraints, members of Sylvester Stallone's family were used to play certain minor parts; his father appears as a bell ringer, his brother was used as a street corner singer and Stallone's first wife was the set photographer.

When Rocky is working out, doing one-handed pushups, Sylvester Stallone only did one. The film was looped to make it look like Rocky did many.