At the end of "A Liking to Biking," Emmy tells Max to be careful about running into the playroom dor, but when she says it, her mouth doesn't move at all.
The ladybug that Ord uses for a helmet in "A Liking to Biking" (and future episodes) always seems to express the exact same emotions as Ord at the exact same time that Ord is expressing them.
In "A Liking to Biking," Ord grabs a white pillow from a pillow cloud, but in Season Two, pillows are colored and found on "pillow trees."
When Max and Emmy wish themselves to Dragon Land in "A Liking to Biking," they don't appear to be touching their bikes. Normally, if they want to take something with them to Dragon Land, it has to be touching them, or touching something that they're touching. Also, when they do get to Dragon Land, they are both touching their bikes.
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.
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.
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.
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.)
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."
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."