PSA: Headscratchers is a place to try and find In-Universe explanations. Try to avoid natter, going too off-topic and/or first person language. If a bullet has something you feel is incorrect, just fix it.
Susan being a 49-and-a-half feet tall and lives in an extremely enclosed space with the other monsters opens up all sorts of uncomfortable possibilities. Does she ever roll over in her sleep and crush the Missing Link? How is the government able to provide enough food for her? Going back to the "enclosed space" thing, how in the world are the other monsters able to put up with her farts? Really! How is her, ahem, "business" disposed of?
The same way they solved those problems for Insectosaurus. And if you ask how they solved her problems, money and an insane amount of high end engineering. Where did they get the money? They opened a highly lucrative fertilizer/methane combustion power plant business that funds a good chunk of their expenses. "When it rains lemons, make lemonade" and all that.
Each monster has its own living quarters. Susan has her own room, as big for her as a dorm room would be for you and me. Each of the other monsters has a proportionally sized room, and even the big room they have communally isn't "extremely enclosed", as it's... well, really big.
They at least lampshade Insectosaurus' waste when Susan upsets him. Link immediately tries to calm him down lest the inevitable flood occurs.
Feeding and maintaining a 50-foot woman seems pretty trivial given government resources, far easier than, say, running a zoo. Even at her size she probably doesn't need as much food as you might think. At 50ft tall she can probably consume, what, maybe 3 cows per day? Regarding dressing her while she was unconscious, however? Mad Science? Lots of cranes?
Insectosaurus looks more like a giant HAMSTER from the advertisements than an insect. What gives?
He's a giant caterpillar. He looks so round partly because he's actually far more round than a real caterpillar. He's far more round maybe because he's overfed, maybe because he's a freakish, mutant, monster caterpillar. Who knows? And in addition to his girth, he also looks round because we only ever see him from one single perspective: the front, and usually below him. Anyone would look round under those conditions. If we had got more aerial shots of him it would have been apparent that he was a caterpillar, but we wouldn't have been able to make out anyone or anything else in those shots.
Why do they call this movie "Monsters vs. Aliens"? There's only one alien, and an army of his (incredibly stupid) clones. Everything else is either a robot or a supercomputer ripped-off from Dexter and Plankton. Obviously it should have been "Monsters vs. Alien".
YMMV but the cloned army is more than enough to justify the final "s" in aliens. If it makes you feel better, the robots are alien robots, from a alien ship.
Plus, Monsters vs. Alien would have been confusing.
If Susan hadn't tried to run away from the meteor, she would've been perfectly okay?
You try thinking rationally when a goddamned meteor is headed straight at you.
If she had stood still or run in the opposite direction, she still would have been the closest person to the meteor. We don't know how the phlebotinum works; maybe it would have made the closest person grow whether she's under it or 50 yards away.
Dr. Cockroach eats garbage like the other monsters, but why? Even if he can eat trash, he was originally human; you'd think that old habits would have made him turn up his nose at piles full of garbage and ask for regular food so he'd never even have a chance to realize newspaper or whatever else is suddenly tasty to him. And one can't imagine that Monger would have denied him it, when he's a decent guy and knows that Dr. Cockroach was originally human.
In Franz Kafka's Metamorphosis, after turning into a giant vermin, Gregor Samsa suddenly finds that he no longer likes his favorite human foods, and prefers old rotten stuff instead. Perhaps it's the same here.
How does one get a Ph.D. in dance?
NYU, Temple, and Ohio State have them, and that's only naming a few.
Why didn't Insectosaurus help out in the battle, and fight the robot?
Insectosaurus, although possessing some intellignece, is ultimately a bug, and while he seems to be the Big Damn Hero at first, he is mesmerised by the lighting eye of the robot (that's how all of the other characters move him around too). As for the robot, he isn't interested in Insectosaurus at all, he's only programmed to get Ginormica/Susan because she absorbed the Quantonium.
Not only that, but Insectosaurus came in from the worst possible angle. There was a bridge full of evacuating civilians between them, with Susan as an intermediary, and they are later joined by their fellow monsters. Apart from B.O.B., Insectosaurus was the only other monster who actually helped Susan in any way (by moving her away from the robot's jaws; B.O.B. helped by removing the dividers, allowing the evacuees to escape from the danger zone and get out of their way).
Susan seems to overlook being a giantess will be less fun than she seemed. Yes, you saved the world from an alien invasion, and while I'm sure that was a lot of fun, how often does that happen? Earthly monster attacks don't seem to be all that frequent either. So the vast majority of her time will be spent in the government facility, doing absolutely nothing, unable to interact without human society without destroying it.
After Susan and the other monsters take down Gallaxhar, they were free from the confinement facility; they can do whatever they choose. In the Halloween special, they seem to share some sort of base and fight off crime whenever there's trouble. And outside of the freedom they now have, her size doesn't really stop her from all that much. She could still do scientific research (might be easier to in some fields). She could still do physical activities. She can still travel the world. The logistics might be a little more challenging, but certainly nothing completely insurmountable. About the only activities she couldn't do without trouble would be anything that requires actual physical contact with another human being and that's a very small realm. Even something like teaching or going to school could be done via Skype or some such.
Why does the Phlebotinum, stated to be the most powerful substance in the universe, not make Susan nearly as large as tiny creatures mutated by regular old earth radiation?
You'll note that Susan is as strong as a robot that is as big as said tiny creature turned huge. Though the Phlebotinium doesn't make her as big as those creatures, it does make her stronger.
Besides a bunch of misunderstandings why are the monsters locked up?
To be fair, apparently most of the monsters have, upon their initial emergence, gone on a rampage. Insectosaurus ate part of Tokyo, B.O.B. ate a bunch of stuff, the Missing Link started kidnapping hot babes on his favourite beach, fought off a few branches of the military and is emphatically unrepentant about what he did; Susan (accidentally) nearly crushed her fiance and a number of others to death. Dr. Cockroach is perhaps exempt, but then again, he is a self-described mad scientist, and is shown at one point attempting to construct a nuclear missile out of building blocks. They're probably too dangerous to let out without training or heavy supervision, except in situations where they are supposed to break things.
Another factor is the monsters' utter dependence on one another not to cause rampant chaos. Insectosaurus is essentially a massive puppy with about the same impulse control, BOB literally lacks a brain, and nearly kills a few people on several different occasions due to it. And Dr. Cockroach...well, he was insane before, and he can only be more insane now.
Monger's explanation was pretty much the reason Agent K gives as to why the presence of aliens is covered up in his movie - the public just doesn't want to know and aren't ready to. Also, while Monger was shown to be pretty cool towards the monsters, there's the good chance that it wasn't his decision to keep them locked up.
Why does Gallaxhar call his army of clones "aliens"? They're not aliens to him, they're the same race as he is.
"Why does he speak idiomatic, modern American-style English?" See Translator Microbes and Translation Convention. Honestly, "alien" as a word has undergone linguistic drift enough that it's YMMV whether it means "foreign", "species that aren't us" or "any species not from Earth".
Susan's hair turned from brown to white when she grew into a giantess, obviously as a side effect from absorbing the quantonium-filled meteor. Why didn't her hair turn back to brown when Gallaxhar drained the quantonium from her, turning her to normal size?
Hair colour comes from little pigmented flakes along the hair shaft—it's why bleaching hair lightens it, as the pigment is more or less stripped away by the harsh chemicals. The quantonium merely flash-bleached her hair to white, stripping it of its brown colour—when she shrunk down again, the pigment was still gone from her hair and wouldn't be brought back simply by removing the thing that removed it.
Also? She probably didn't have ALL the quantonium removed from her system. Just 99.9%...which having white hair shows.
There’s also the popular urban legend that exposure to a traumatic event can turn your hair white .
Why did most people at the wedding start treating Susan like a monster the first moment she turned into a giant? Hasn't she met and known those people for a time before it happened? I mean, sure, you have to get outside in order to, you know, safely avoid collateral damage, and probably the government, who arrived just before that incident, apprehended those people away from Susan as they are capturing her.
Because she was glowing and knocking down the building around them while she was turning into a 50-foot monster. They are not in a situation where calm and rational thought is going to prevail. Plus, it's not like they knew she was still cognizant (somerhing something zombies).
How did the people at the facility manage to undress Susan and re-dress her while she was unconscious? Changing an unconscious person's clothes is difficult at best, and when the person in question is that big, it would be a truly, well, enormous challenge.
One way to solve this challenge would be to cut her out of her wedding dress to undress her, then drape cloth around her and sew the hemlines, etc, onto her. Essentially make the clothing around her. At that size difference, this would be much easier than trying to move pre-sewn clothing around, let alone dress her. The real question is why would they go to that much trouble? It would be much easier to leave her in her wedding dress, leave the clothes in a pile next to her bed, and when she wakes up say "Please change into the clothes provided and place your soiled clothes into the receptacle." If they really needed to get her out of the dress right away (say they need to study it for the Phlebtonium it may have absorbed), it would be much easier to dress her in a hospital gown and made her change when she got up. That's kinda the point of hospital gowns.
How long was Susan knocked out by the stuff in the oversized needle? Long enough to move her from Modesto, obviously, but how long after that? Long enough for them to make/obtain clothes for a 49-foot-11 1/2-inch tall woman? And construct a table and chair for her proportions? While having rooms the right size for her is believable (Insectosaurus's presence proving they deal with giant monsters occasionally), having the rest of the stuff on hand is stretching things beyond Crazy-Prepared.
Maybe it's like Area 51 in Kim Possible, where the staff were even prepared for the ridiculously unlikely scenario of being attacked by a giant poodle and rescued by a giant naked mole rat; considering their experience of monsters, they probably had some kind of resources available to be prepared in the event of encountering a giant human.
