Ear Worm: "Close your eyes, shut your mouth, dream a dream to get us out, dream dream dream dream dream dream..."
Fridge Brilliance: The Conspicuous CG is one of those tropes that breaks the illusion, and therefore the viewer has no suspension of disbelief... but that's the point; you're not supposed to think Planet Drool is real. The audience is just like the rest of the adults in the film that think Max's dreams are ultimately fake. It's not until Sharkboy, Lavagirl, and Mr. Electric come to Earth at the end that their existence is validated.
Lavagirl's representation in the real world (besides Max's mother) is a lava lamp.
When Sharkboy and Lavagirl first arrive in Max's classroom, Sharkboy pretty blatantly attacks Linus and rips up his paper. Now, that could just be his shark instincts acting up, but why would Linus have that effect on him? Well, considering the Big Bad for most of the film is Linus's counterpart...
The reason why the protagonists can't defeat Mister Electric with the Crystal Heart is because it can only be used by the Ice Princess, whose father won't let her out of the castle. At the climax, Mr Electricidad has to let Marissa go out to defeat Mister Electric.
Why could Max not do anything special like Sharkboy and Lavagirl until towards the end? Simple. He didn't realize he was asleep and dreaming until then. It's a lot like lucid dreamers, since, unless you realize you're dreaming, you're bound to how you are in real life in your dreams. Then again, he's surprised when they tell him he's dreaming afterwards, so...
Ham and Cheese: Those who don't like the movie will love Linus/Minus' overacting.
Tear Jerker: Max crying over Sharkboy and Lavagirl, who appear to be dead.
Toy Ship: In-universe examples: Max with Marissa and Lavagirl with Sharkboy.
The Woobie: Max. He's a bully magnet and just wants to be left alone to dream in peace. Interestingly inverted at the end when his own invention makes him realize that he's only been dreaming for himself and didn't care enough about others, implying that everyone else needed his help and The Woobie was actually all of them.
They Wasted a Perfectly Good Plot: So Sharkboy gets his own origin story, having been raised part of his life by sharks. What's Lavagirl's backstory? Never explained in the movie.
While Sharkboy is, I think, established as being a real person from Earth, which explains why he was able to break out of the ice after Planet Drool shut down, Lavagirl's implied to be born from Max's dreams, since she takes Sharkboy from Earth to the other planet, which would have it make sense to why when she gets revived and so does the planet when she gets thrown into the lava to revive her, since they could be linked in some way. Plus her hearing Max tell her what she really is only makes sense if she originates from his dreams.