Revealing mistake: When Apollo and Rocky are analyzing the "game film" of Rocky's first fight with Clubber, the film they are watching is actually movie clips of "Rocky III" itself. This is evidenced by the variety of angles and in-the-ring shots. In an effort to disguise this trickery, the "game film" was made black and white. (01:02:45)
Revealing mistake: When Mr. T and Rocky are about to fight for the second time, the camera shows a view of the crowd, if you look closely in the top left hand corner there is a billboard with Rocky and Apollo with superfight 2 on it. This is a scene from Rocky 2.
Revealing mistake: In what is supposed to be an emotionally significant scene, Apollo offers his USA style boxing trunks to Rocky for him to wear in the upcoming rematch with Clubber. Problem is, there is one flashback scene when Rocky is training with Apollo that shows Clubber hitting Rocky with a body shot. You can see the top two or three inches of Rocky's trunks below the waistband and it is clearly the red, white, and blue trunks. In fact, the scene is from the second fight. You can see it in normal speed later.
Revealing mistake: During the rematch at the end of the film, Rocky is taunting Clubber with insults, and he reaches up and rubs Clubber's mowhawk a couple times to irritate him. The second time Rocky reaches for the top of Clubber's head, he can't quite reach it and Clubber just stands there and waits for an unrealistically long time for Rocky to reach the top of his head with his hand, and he makes absolutely no attempt to block or counter what surely would have been interpreted as a possible punch by any real boxer. This is certainly not the way any 'World Champion' would react in a real fight.
Revealing mistake: As the montage showing Clubber's rise to first-rank status is shown, various newspapers are shown detailing certain fights. When the shot of the paper with the article titled "Clubber Lang beats Jaffe in brutal 6th KO", look at the actual writing on the newspaper: It is nothing but about two paragraphs of meaningless, court-room style legal gibberish, and has absolutely nothing to do with boxing in any fashion. These two paragraphs are randomly printed over and over for every article shown on the paper.
Revealing mistake: Rocky, Apollo, Adrian, and Paulie are filmed from behind walking to Apollo's gym (notice Rocky and Apollo are the same height). When Rocky turns to walk in the door, you see heels at least three inches tall on his feet.
Revealing mistake: During the movie's opening title sequence, Clubber Lang knocks out Jaffe in the sixth round. If you watch carefully, you can see that Lang's boxing glove actually hits Jaffe's shoulder, but he still knocks him out in the process.
Revealing mistake: When Paulie throws the bottle at the Rocky pinball machine at the beginning of the movie, the glass smashes but the bottle doesn't, indicating that the bottle is an obvious prop.
Suggested correction: Liquor bottles are small and dense and much stronger against damage than a thin sheet of plate glass.
Revealing mistake: Look closely after Thunderlips powerslams Rocky. Mainly when he pulls him up by the hair. Clearly that's not Sylvester Stallone but a stunt double.
Revealing mistake: In a shot of Clubber Lang and his manager standing in the corner at the end of the first round during the rematch between Lang and Rocky, "Clubber" on Lang's boxing shorts and "Heavyweight Champ" on the manager's shirt are back to front, indicating that it is a reversed shot.