In Rocky IV how does the Creed vs Drago fight go on?

Simply, it wouldn't have. Remember, this is an exhibition bout. While the rules aren't as strict as a normal bout, they also expect the boxers to "behave". It would have been ended under normal circumstances with any of the above mentioned infractions, although there's an outside possibility it could have continued if both boxers argued for it.

Those sorts of technicalities happen over and over and generally go unnoticed by the majority of the viewers. The DQ notes are interesting, but I think even as a casual viewer who has seen a few boxing and UFC fights I would pick on the stamina more than anything.

One thing to consider is that even in real life, a foul has to be called by someone. If it is missed or ignored, the game goes on. Maybe in the fiction of Rocky, those involved were told behind the curtain that the show must go on. Better to have an exciting fight than to have to deal with a few thousand refund requests and bad publicity. So ultimately, who knows?

Think of how many times people shoot guns in movies. Sometimes, someone pumps a shotgun several times between shots. You know what that would do? Sometimes they pull hammers back when the hammer would already be back. Sometimes they don't have to reload, like every John Woo movie ever made.

How many times have you seen a car jump anything in a movie? Want some fun? Google the closing credits to the Dukes of Hazzard movie and watch how many General Lees they trashed trying to capture crazy jumps. Basically, that would happen every single time any car jumps something and to actually not crash would be the odds heavily against you.

Military and police ranking is a good one too. So many movies just slap ranking things on uniforms and pretend they line up. People call BS on rotten tomatoes reviews all the time but yet it still goes on.

In the end, the cost/benefit ratio is simply too far disjointed to care to rectify in the majority of cases. Some authors, like Andy Weir who wrote the Martian, go out of their way to scientifically confirm all the details in their story because the details are what they obsess over and in many ways are what make their stories so good. In others, like Rocky, you can skirt it a little because the target audience is the average movie goer, not a professional boxer. So to pay all the extra consulting, observational, and post production validations on any given movie that isn't professing scientific accuracy may be too far outside the desired expenses for most production studios. Hell, I would do that too. If I wanted to make a movie about a hellish rock climbing story I might go for about 80% on the realism thing. Anything more and I would never finish the story. Hell, I may not even start it.