Corrected entry: At a swimming pool for juvenile swimmers - especially with such a water slide - the pool would have to be sufficiently deep to accommodate visitors comfortably. Yet Ben/Grey Matter seems to be standing on the pool's floor with ease, given that he is six inches tall and about two inches (his head) are above the water, since he makes no swimming movements. And despite all that, Howell Waynewright is able to fully submerge *and* grab Ben from below instead of from behind, which he would have to do if Ben had been swimming.
Tourist Trap - S1-E6
Corrected entry: One of Sparkville's 'giant' attraction is a huge ketchup bottle - filled with ketchup. It would rather be strange to keep the stuff - or even just paint - in a huge bottle out in the open, since it would either spoil, evaporate or dry up, and refills would come too expensive for a container this size.
Correction: It wouldn't evaporate as ketchup's a paste, not a fluid. It wouldn't dry up as long as the lid was on it. It wouldn't spoil as long as it had never been opened (ketchup in the grocery store isn't refrigerated). There's no reason not to have it full. And every reason, even if they must refill from time to time, to keep it topped off: tourist money.
Correction: Gray Matter is an alien, he could very well be less dense in water which would cause him to float.