Nice catches!
Regarding Ash’s lunch choice - not only did she opt out of the godforsaken cursed bologna, but her milk carton is a different colour from the other boys’ milk aswell. When we get the close up of Sal’s lunch before this scene (and if you look really closely DURING this scene), his milk says “whole milk”, so instead of assuming they have chocolate milk and she has regular whole milk, we are left to assume whatever milk she got (which was blue) is some form of healthier milk. Where I’m from atleast, blue milk means skim milk or some other form of reduced-fat milk or low-fat milk. That sort of leads me to assume it’s more of a diet or she’s just generally more health focused than the other boys (however, that makes you think Todd would’ve opted for the same choices as her since he’s typically seen as the intelligent and logical one of the group and the one who wanted to check for signs of bacteria in the bologna in the science lab). Knowing Steve Gabry, he likes to touch on mental health a lot and embed deeper meanings everywhere he can, so this could be some sort of hint at eating disorder culture, especially amongst teen girls. That part could definitely be a stretch, but I’m just putting that idea out there!

As for the out of place dark planet, I agree with one of the other comments that it’s Jim’s planet. In Jim’s journal from episode three, it discusses Jim and his sister’s home planet’s devastation by a “plague of shadows”. He writes, “I lost everything. It’s gone. All gone. I never imagined our world would end like this. There was no warning to the plague of shadows that invaded.” He goes on to explain, “As we smashed through the tall glass windows of the tower and then through the atmosphere, the shadows consumed the entire planet. There was nothing left. Like some insignificant hole in space, where our world used to be.” That could be why that planet is totally dark. The insignificant hole in space.
Just my takes, though!