Continuity mistake: Rocky's eye was injured at the fight in the beginning of the movie. They show the right eye covered up with the bandage at the hospital, but no one says specifically which eye it was. When Rocky decides to fight Apollo again he goes to see Mick. Mick the trainer tests both eyes. He tests the left and it tests OK, then he says, "Now we try the other lamp." The right eye is the one that has no peripheral vision. Mick slaps him on the right cheek to prove how he would get hurt by Apollo. When he does train him, Mick tells Rocky to switch to fighting right handed. Mick says,"Now, this will confuse Apollo, and it will protect that bad eye." However, in the fight at the end the announcers says that, "Apollo hit that bad left eye, remember from the first fight. It's the same eye that was cut the last time." (00:47:40 - 01:43:15)
Revealing mistake: In the fight against Apollo, Rocky's last punch of the second round conspicuously misses by a mile, but Apollo nonetheless acts like he has been punched, and there is a punch sound effect as well.