I can't believe that Flynn was more idiotic that Thomas from Wonky Whistle. Flynn was so out of character on this one, like really so out of character.
Compared to them, Thomas was mishearing the humans and Bertie and thought that they were saying hello even though they aren't, and also by the fact that he left at the moment where the workmen were about to fix his whistle, showing how impatient he is, but nevertheless, Thomas does redeem himself after causing a mistake.
For Flynn, he is supposed to be a good firefighter, yet in this episode, he was the complete opposite. He irresponsibly decided to show the Diesels that he is busy, even though he is always busy. Just because someone teases you for not doing stuff doesn't mean you have to do it right away.
Also not to mention that he didn't listen to Rocky, and he wasted all of his water, so he couldn't save Thomas. Boo-hoo.
Also, the most infamous thing is that the Narrator said "His firebox was on fire!". What's the point? Fireboxes do have fire in them, so it is not dangerous at all and what the Narrator said was nonsensical.
But there are some good things in the episode, like The Fat Controller yelling "BUT I'M WET THROUGH!!!", that was so damn funny. Everyone else besides Flynn and the Diesels are all good characters, and as always, the ending is good.
So I have to say that in my point of view, this episode is like the worst one for me, more worse than Wonky Whistle.