Adorkable: Pickle with his nasal-voice and naive nature.
Base-Breaking Character: Crusher is either incredibly enjoyed due to his Large Ham behavior or incredibly disliked for the fact he constantly doesn't see his cheating ways lead to him failing every time. Special mention to his Manchild cries whenever he loses.
How do the monster machines eat if their mouths are just their grill...?
Crusher is known to be a cheater, but since Blaze wins by passing him with his Blazing Speed, wouldn't that be cheating, too?
Idiot Plot: The point behind Blaze getting trapped in the cave in "Dragon Island Duel". Being a Voluntary Shapeshifter, he could've just transformed into something to free himself, but he has to wait until AJ finds him to realize such.
Memetic Mutation: The infamous "Call Blaze" app on the Google Store that scared kids became this. note Every time one would beat the game, someone only known as "Happy Slappy" would call you, threatening to stab you to death with his knife. Needless to say, this was a cause of concern for many parents with children who were left terrified by the unsettling call. The app has since been banned from Google Play.
Said song is also to the tune of "Henry's Underwater Big Band" by The Wiggles.
They Changed It, Now It Sucks!: Some viewers didn't like a number of the changes after the mid-season 3 Art Evolution, such as having AJ describe the STEM concept instead of Blaze, a digital diagram of AJ's description appearing on his watch or Blaze's control panel instead of skywriting it, and not using his Visor View to see something faraway, instead having the camera panning to whatever is being spotted when he says it.
Although Blaze's friends get a lot of attention, their appearances gradually became fewer with each new season, almost as if they became Out of Focus. None of them even get a chance to sing a full song in the series (aside from a few brief moments in the first season).
Starla is suffering this the worse. She's appeared the fewest out of the main characters, only appearing no more than 5-6 times after season 1. She's also had the longest absence streak with a grand total of 14 absences, between "Toucan Do It!" in Season 3 to "Robots to the Rescue" in Season 4. This is probably because Kate Higgins had a lot of other shows to work with at the time.
As a matter of fact, the fourth season contains the longest consecutive set of episodes that only feature Blaze, AJ, Crusher and Pickle — five in a row from "Officer Blaze" to "Blaze and the Magic Genie". It appears that said quartet of main characters have became the "official" set of main characters for the rest of the show's run, and the others have been demoted to recurring roles.
Watts was built up as Blaze's new Monster Machine friend, but she appeared very little in the fourth season, only four out of twenty episodes. Possibly because Melanie Minichino had a lot of work as the female announcer for Disney Junior, as well as her roles as Anya and Ava.
Crusher suffers this Up to Eleven in "Toy Trouble!", having no more than two minutes throughout the episode's main story, with the only purpose to cause the conflict. To top it off, Blaze and his friends were unaware of his presence, and never found out he was the one who made the giant toys. They also don't bother to give him one of the toys after they shrunk them and all was taken care of.
They Wasted a Perfectly Good Plot: The Monster Machines competing in a night race in "The Midnight Mile" would've been a good time for them to use their speed lights again (having received them in "Light Riders"). Instead, they race on a lit track with no lights on them at all, and thus, the speed lights have became Forgotten Phlebotinum all together.
Uncanny Valley: The faces of the trucks can sometimes come off as this, especially the exaggerated Animesque moments in Season 1.
What an Idiot!: The show has some moments, despite being a children's series.
In "Axle City Grand Prix", Crusher steals Gabby's remote that lets her control any machine so he can try and win the titular race. In one of his cheats, he turns on a bunch of cranes which block Blaze's way with pipes. You'd Expect: For Crusher to double check the pipes to see if either one is big enough for Blaze to easily drive right through. Instead: He disappears right after the pipes are laid out, and once Blaze encounters the pipes, Gabby immediately realizes he can drive through the biggest ones and he does just that.
In "Dinocoaster", Zeg gets a ticket so he, Blaze and AJ can ride the titular ride. All of a sudden, a kid truck drops his ball and it bounces away, and Zeg offers to get it. You'd Expect: Zeg to put his ticket in a safe place or have Blaze and AJ watch it for him. Instead: He leaves the ticket unattended on a barrel. You'd also expect: Blaze to bring the ticket to Zeg after he returns the kid truck's ball to him. Instead: He leaves it where it is, and a wind sweeps it up and away into Axle City, kicking off the plot of the episode.
In "Power Tires", Blaze is given the titular tires after an accident causes his regular tires to get ripped. Throughout the race, Crusher notices Blaze is catching up and tries to stop him. You'd Expect: For Crusher to think twice before he puts his cheat underway, as they always have a short flaw in them somehow. Instead: He goes with it anyway, and no matter what he sends out, Blaze will use the Power Tires to get past the cheat based on what he turns them into for the obstacle.
In "Officer Blaze", Blaze has to deliver a cake to a birthday party and throughout the trip, he comes across several traffic jams on the streets before him. You'd Expect: Blaze to simply use the sidewalk to get around the jams. Instead: He uses his siren to tell the trucks to move, possibly to advance the plotline.
"AJ to the Rescue": Blaze chases after a monkey's runaway kite, not going far from AJ, only to fall into a mud pit and cannot get out. You'd Expect: AJ to go the same way Blaze did and arrive where he is in no time. Instead: He follows a different route, and thus, it takes the whole episode before he finally reaches Blaze. You'd also Expect: For Blaze to use his Blazing Speed on his own without AJ (since he's done it before in "Treasure Track") to quickly free himself. Instead: He stays stuck until AJ arrives and gives him the Blazing Speed power while in the driver's seat.
In "Babysitting Heroes", Stripes turns on a bubble machine which makes bubbles for the baby animals to play with, then one pops against a book on the shelf, which causes it to knock over several toys in a chain reaction finishing with a toy train driving right off the shelf toward the bubble machine. You'd Expect: Either Blaze, AJ or Stripes to run and pick it up. Instead: They stay where they are, leaving the train to turn up the machine's power and trap the animals in giant bubbles, kicking off the plot of the episode.
In "Toy Trouble!", after all the giant toys were shrunken and taken care of, Blaze and the gang decide to play with them. You'd Expect: For Blaze to give one of the toys to Crusher, given the fact that he never gets to play with anything throughout the episode and deserves it. Instead: They keep the toys for themselves. Bonus Points: Blaze and his friends were completely unaware of Crusher's appearance, and never found out he was the one who made the giant toys in the first place! You'd also expect: For Crusher and Pickle to hide along the sidewalk when being chased by the giant toys, so the heroes can find them and tell them the truth. Instead: They escape down the nearest street, leaving the heroes none the wiser to their appearance, and Crusher gets away with the trouble scot-free.