Other mistake: About half way through the movie, Adrian gives Rocky a dog (Butkus). The second time Rocky goes to the meatpacking plant, the dog is with him when he walks in, but he walks out alone and the dog is not seen again in this movie.
Suggested correction: How is this a mistake? Rocky could easily have left with the dog on another occasion. It's like saying, sometimes Rocky is shown in a location but it's never shown how he got there. That isn't a mistake, it's just what happens in films. Also, the dog not being seen again is irrelevant.
Other mistake: After the 2 Yankees put ketchup on Lupus' head, Tanner sticks up for him. After the Yankees put Tanner in the garbage can, there's obviously more ketchup on his head from before, along with ketchup on his shirt that wasn't there before either.