In "The Jumping Bean Express," if you pay attention to Fernando's dragon badge, you'll notice that it changes colours in each of the scenes that he appears in.
There are 2 captioning errors in "Quibbling Siblings." the first one is seen after Wheezie was playing drums in bed. When she sees Max and Emmy, she says in the captioning, "Hi Emmy! Hi Matt!" The other is when the four were searching for the jugglebug. When Emmy asks Zak how it sounds, Zak in text says, "Well, it sounds kind of like.. kinda like... (Jugglebug does its sound.) .. Zak!" It should obviously be "That!"
Apparently, the same "Max and Emmy transport to Dragon Land" sequence was used in "Follow the Dots" and "Smashing Success," since Max and Emmy were holding flashlights for no reason in "Follow the Dots."
After Emmy announces that the dragons are calling in "Follow the Dots," the activity books that she and Max were working on magically disappear.
Cassie usually shrinks when she feels scared or sad, but in "A Smashing Success," Cassie never shrinked when she was blamed by Wheezie.
In "It Happened One Nightmare," Cassie states that she has 74 brothers and sisters. But in her theme song, "Cassie," it's stated that her brothers and sisters total 72, as well as in Season Two episode "Dragonberry Drought."
In "A Cool School," when Cassie calls for Zak and Wheezie, she sounds like Emmy.
When Max says that Quetzal's salsa is spicy hot, "just like my abuelita's salsa," close-captioning reads "grandma's salsa." Additionally, Zak's name is spelt "Zack" on close-captioning throughout the episode.
Looking at things through 3D glasses doesn't make the colors of the objects get displaced - instead, evertything will look red, brown and green (or red, brown or blue, depending on your glasses' type).
(Agent0042's Note - Looking at things through 3-D glasses won't make images appear where they normally wouldn't be either. I suppose maybe they're magic 3-D glasses that work different from normal ones.)
When Zak is convincing himself that he must learn to catch in "Dragon Drop," his teeth are the same color as his skin.
In "Dragon Drop," when Zak misses catch the ball that Emmy threw and says he can't take it anymore, the ball returns to Emmy's side, even though nobody is shown to have given the ball back to Emmy.
Cassie's hair ribbon keeps disappearing and reappering when Quetzal is drawing names.
Zak and Wheezie's badges are reversed many times during "A Feat on Her Feet," including when Cassie commented on the wagon being broken, when Wheezie said "Let's rock and roll!," and when Zak asked Cassie if she wanted a pillow to help with her skating.
When Zak and Wheezie first go into the treehouse in "Zak and the Beanstalk," their necks reach higher than the top of the treehouse, which is a mistake, considering that in all other episodes, they were shorter than the treehouse. Additionally, the part of their tail sticking out of the treehouse magically disappears when Sid starts ascending into the clouds.
When Emmy throws bread crumbs for the do-re-mi birds in "Zak and the Beanstalk," Zak's side of his and Wheezie's tail is purple.
This one only applies to the ep aired in Malaysia on April 2, 2002: The local TV station mistakenly captions Cassie as "Katie" and Emmy as "Amy". Then again, Cassie and Emmy are rare names in this part of the world.
In the "Wiggle Song" segment, when the dragons are flying around the Stickleback Mountains, Max is on Ord's back. But in the next frame two seconds later, Max is somehow riding a blue stock dragon, while Ord is sitting on the ground waving to him.
Zak and Wheezie's hats keep disappearing and reappearing when they're digging for Scaliwag's treasure under the schoolhouse.
The face on Scaliwag's drawing of Sid Sycamore changed direction the last time it was shown.
After Scaliwag tells the gang that he's not a pirate, the hook that he just placed on the doorframe disappears.