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 Lavagirl's hair is on fire due to her anger, Sharkboy splashes her hair to put it out. Between shots her wet hair instantly dries and becomes fluffy and neat. (00:57:30)
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: 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)
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.
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.
Revealing mistake: In the Milk River scene, you can see the cherry on the sound stage they are recording on.
Other mistake: Lavagirl burns everything she touches, but in some shots she touches Max's shoulders and doesn't burn him.
Continuity mistake: When Minus has the heroes captured and hanging down from wires, there is a shot where he is threatening Max and Sharkboy is nowhere to be seen. There is no wire either, so it's not like he's out of sight.
Answer: According to Taylor Lautner, the actor who played Sharkboy, he approached the role as if Sharkboy was jealous of Max because Sharkboy has a crush on Lavagirl and she pays Max lots of attention.
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