This is what happened in the 2018 world championship in Atlanta.
Unger won* by a fraction of a point (a fraction of a second). But there were two cuts that were judged wrong.
One was a foam pool noodle. The competitors were supposed to make three cuts. Due to the heat the noodle was soft and falling off the post and people weren't able to get three cuts. But the rules stipulate that if you don't get your cuts you still have to make three air cuts, otherwise you're penalized for passing the obstacle. Dan knew this from experience because he had lost a big race once due to it so he cut the air like they were supposed to. Unger claimed he thought he did too, but you can see in the video he didn't. The judges decided to let it slide due to the heat, but had Dan not paused and taken the cuts he'd have won on time alone right there. So he lost there because he followed the rules. The judges made an error there but the other error is larger:
The other judging error was in a rope slice and chop. This obstacle is worth 15 points (which is probably about the spread from 1st to 3rd). The cutter makes once slice on a horizontal rope, then another which frees it. This is difficult to do without knocking the rope off. Then, if the rope is still sitting on the board and wasn't knocked off on the last slice the cutter can then chop the center of the rope. That chop is easy but setting up for it where the rope is still sitting there and wasn't knocked off during the slice is very difficult. A common mistake is to slice, slice and not realize one of the slices was incomplete and then chop a rope that wasn't cut free yet. This is very common and you can see in the video that this is what happened to Unger. It was plain to see. But, after his chop cut he went back and finished the slice. Neither that chop nor that slice should count, you can't go back and make that cut after-the-fact but he did. Folks chalked it up to a harmless heat-of-the-moment brain fart and assumed he wouldn't get those points, but the judge either didn't see what happened clearly or perhaps was concerned he misremembered and asked Unger what happened. And Unger apparently misremembered too because they gave it to him which gave him the race. People saw this and it's pretty clear to me and most everyone else what happened by viewing the different videos. But they don't view video evidence and they don't change the outcome. So, an inexperienced judge and some fuzzy heads screwed this up and Dan didn't get the win he earned. They're implementing changes going forward but there is no do-over here.
^ An example of the sort of cut in question
You can't go back and free the attached end after-the-fact.