Trivia: 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.
Trivia: 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.
Trivia: 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.
Trivia: During filming of the final fight, Sylvester Stallone and Carl Weathers both suffered injuries, with Stallone suffering bruised ribs and Weathers suffering a damaged nose. Stallone's injuries forced filming to be put on hold for over three weeks for him to recover. This happened as Stallone wanted the final fight to look believable and tried to make it real.