Near the end of "Ord Sees the Light," Ord's dragon badge glows. It's the entire thing though, not just the round, crystal section in the center. This is the only known episode in which that happens, making it a definite mistake.
When Max and Emmy arrive in Dragon Land in "Ord Sees the Light," Emmy is still holding the dragon scale. This is a mistake; it is supposed to go back into the box in their playroom to be used when they go again. Thanks to PBSKidVid for spotting this mistake.
When the magic crayon drew more crayons, why couldn't the new personified crayons be used by everybody?
When Wheezie gets impatient with Ord at the concession stand, she tells the dragon there to give them two of everything- and he does! This is all on their ticket?
Ten minutes is a very long ride on a roller coaster.
In "Roller Coaster Dragon," the ticket-taker said that it would be ten minutes before the coaster got back and then started an hourglass. He then said that there were eight minutes left, but before he said that, more than half of the sand had reached bottom of the hourglass.
This is the second time Emmy says the rhyme to get to Dragon Land by herself. The first time was in Tales You Lose.
At the beginning of "My Emmy or Bust," Max calls for Emmy, who's just left with Dad to go to the store. Mom asks if he was calling for her and in a voice not much lower than that with which he called for Emmy, he talks about how he's going Dragon Land. Does his Mom hear him?
Logic indicates that the gang should not have to repeat the step of rubbing the fairyberries on themselves in "A True Blue Friend."
No reason is given for Zak and Wheezie having something as troublesome as this "permanent paint."
When the group makes snow angels in "A True Blue Friend," they do not show any sign that they are getting cold. However, in other episodes, they usually do act as if they are cold when in the snow in Dragon Land.
Say, Wheezie has a do-re-mi bird whistle? She ought have tried using that back in "Zak's Song."
Cassie seems strangely unsupportive of Wheezie's position in "My Way or Snow Way," even exclaiming rather in a rather annoyed tone: "It doesn't work!" It's not like Cassie hasn't been in Wheezie's shoes herself.
One of the ways that Max, Emmy, and the dragons use to track Nippy is to follow his pawprints, but when he comes bounding up to Wheezie, he doesn't leave any pawprints.
Zak and Ord never get their turns in "Quetzal's Magic Pop-Up Book," suggesting a rushed ending.
In this episode, Ord mentions that he has a sister. However, in "It Happened One Nightmare," he said he didn't have any brothers and sisters.
When Zak and Wheezie fall into the muddy creek, they're completely covered in mud. As Emmy, Max and the dragons are assessing the situation, the camera cuts to Cassie for a few seconds. When the camera returns to Zak and Wheezie, they are completely clean.
In "Wheezie's Last Laugh" when everyone gaps after Mister Pop suddenly appears, Cassie can be heard gasping as well, however she was not in that episode.
Max's hanging a picture of frogs with unicorn horns on the playroom wall is probably inadvisable because either his Mom or Dad could come in and see it any time.
At the beginning of "Prepare According To Instructions," the dragons are all asking Quetzal about what he's about to tell him about and Ord asks if it's better than ice cream. As he saying this, Max and Emmy are materializing in front of them and yet Max comments on what Ord said, like he heard it. Past history indicates that Max and Emmy can't hear anything being said until after they had materialized.