Continuity mistake: In the opening shot at the breakfast table, there is a large cereal box and a carton of milk on the right side of the table, in front of two salt-n-pepper shakers. But during the scene it continues to swap to an angle behind the two shakers - but now the cereal box and milk carton have vanished, so as not to block the view for this angled shot. (00:12:30)
Continuity mistake: When Sharkboy and Lavagirl burst into the classroom looking for Max, there is writing on the blackboard ("Science, Chapter Two") written in yellow chalk. Strangely, later in the scene the writing is now written in white chalk, and the handwriting of the text is noticeably different. Then, later it goes back to yellow! (00:16:45 - 00:17:40)
Revealing mistake: When Lavagirl burns the diary, it goes up in flames. However, if you watch Max and Sharkboy, they look at an unseen object falling to the ground. The unseen object is the diary, taken out in editing. Later, Max looks back at the diary on the ground.
Continuity mistake: When Max is about to climb up the tower of ice to retrieve the Crystal heart, Sharkboy hands him his left glove. But in the shot of Sharkboy falling down the ice tower, both his gloves are back on! (00:59:25)
Revealing mistake: Near the end, Max's father is holding onto a tree to avoid being blown away by the tornado. However, the next time you see him he starts to talk to Max with both of his hands off the tree and he isn't being affected by the incredibly strong wind at all.
Continuity mistake: At the end, where Marissa has just defeated Mr. Electric, Linus runs out of the room and into the snow. It's not the actor but instead a double running out of the room. In the next shot, he pushes past Max to get out of the classroom again.
Continuity mistake: When Max throws his dream journal towards Linus in the classroom it falls on the floor by his desk, but in the next shot it has reappeared on the desk in front of Max! (00:16:40)
Revealing mistake: When Sharkboy is running at a fast speed to get Lavagirl to the volcano, in one shot as he runs with her cradled in his arms, it is clearly not her, but a dummy. (01:07:25)
Continuity mistake: When Lavagirl sneezes on the bridge to the Ice Castle, she causes Sharkboy to fly across in the air and he ends up dangling from the side of the bridge. In this shot his back fin is completely gone. But instantly in the next shot it has reappeared again, fixed on his back. (00:49:30)
Continuity mistake: When Mr. Electricidad tells his daughter Marissa to not go to recess, as she replies, and the Max talks with her, her plaited ponytail continues to swap from laying on her left shoulder, to hanging down her back. (00:15:25)
Continuity mistake: When Lavagirl is spraying Mr. Electric with lava, the position of her arms continues to change, from which one is outstretched and changing from being outstretched, to at her sides. (00:27:40)
Audio problem: When Max's mother is walking him down the path to school, in one shot as she says "Sorry, I didn't mean to dump all this on you right before school," her mouth is in shot and doesn't move to the audio. (00:14:05)
Continuity mistake: When Max finds the plate of burnt and eaten cookies, he picks up one with shark bites in it. When he picks it up again to show his mother, the bites are different. (00:09:55)
Suggested correction: He probably picked up a different cookie.
Continuity mistake: After Mr. Electricidad tells Max off for talking to his daughter Marissa, as Max walks back to his seat Marissa's arms goes from crossed at her chest, to uncrossed with her left hand supporting her head. (00:16:00)
Continuity mistake: At the end of the scene in the kitchen where Max finds the eaten cookies, as he is walking back upstairs the carton of milk on the counter suddenly disappears between shots. (00:10:10)
