I'm not disagreeing with your theory but the Maractus episode seems too unusual, I'm just not quite understanding it.
If it took place after the gym, then I think it would have to be more than just script changing to explain it.
The animation works that Ash thinks he's in Driftveil City, but he learns that he's not.
Now assuming the animation didn't change, why is Ash excited? Was it really Mistralton City he thought was in, even after one episode? I'm not sure I buy that because I would assume then that Ash would be close to the town/city before claiming he was there, and odds are it's going to be one giant trek before we reach Skyla, and I'm sure that's ignoring any possible episode switch-ups.
So I just don't quite buy it. If the animation was the same, and Ash was initially excited about the gym and it was the Mistralton Gym, there's just some logic problems with it, because he couldn't just leave Driftveil City and the next location he goes to is Mistralton City, granted Ash could be THAT stupid, but I would presumably think they checked a map first and at least between Nimbasa City and Driftveil City there's just a bridge, so that would make way it would be sensible that it would be Driftveil (ignoring anime-exclusive locations). Because there's a whole lot of crap going on between Driftveil and Mistralton, like the Chargestone Cave for example.
However if that whole scene was changed (animation-wise), then it might make more sense, assuming the original scene was Ash checking out his badge, making some stupid comment, and then cue the Maractus part.
Overall the biggest problem I have with it, is if it actually took place just AFTER the gym, unless it was animated differently. If it was merely a script change, I'm just not sure it makes any sense given Ash actions in beginning, and assuming they were similar, just different gyms.