How come that Carole and Tuesday know virtually nothing about the music scene, considering their love for music? The only artist current to their time they seem to recognize is Crystal, who operates in a genre completely different from theirs. They also seem to lack any knowledge of older music, including the Beatles.
They seemed to recognize at least some of Gus's name drops when speaking about his credentials, and Tuesday is familiar with Cyndi Lauper. I'd say that their music tastes probably gear to older stuff, mostly things that were written by people instead of AI. Crystal would be the exception because she's just that good, and is popular enough that everybody would know her regardless of music tastes.
They didn't know The Beatles' producer, they never said they didn't know who The Beatles were. Gus was trying to explain how important the manager and behind-the-scenes people are to a successful band, and unintentionally pulled an Appeal to Obscurity.
How far into the future does this show take place? Considering we have yet to send people to Mars we can assume it takes place at least a hundred years from now. Yet Gus claims to have worked with Bruno Mars and Justin Bieber, and Motörhead seems to still have been relevant enough to be mentioned in an article about him. Which takes us to ...
The official description for the show states that the show takes place 50 years after people began migrating to Mars. Tech and culture on Mars is insanely advanced, so the show can only logically take place in an alternate version of our universe, where technology is further advanced. Next, assuming the show takes place fifty years from now, (or rather, 50 years from their 2019), then it wouldn't be hard to imagine that these people were with Gus at one point during that time.
Gus doesn't say he worked with Bruno Mars, he said he worked on Bruno's Mars show. As in the Mars show for a musician named Bruno. This is a pun based on Bruno Mars' name and the Martian setting.
Gus' age
How old is Gus? If he has worked with Bruno Mars, then he should be ancient. Suddenly he doesn't really seem to look that bad with this in mind.
The obvious answer for those two questions would be that the show doesn't just take place in the future, but in an Alternate History.
I posted this above, but Gus doesn't say he worked with Bruno Mars, he said he worked on Bruno's Mars show. As in the Mars show for a musician named Bruno. This is a pun based on Bruno Mars' name and the Martian setting.
Playing a collector's item?
Why does Carole play a Nord Lead keyboard from our current timeline? By the time this show takes place that keyboard would probably be considered a collector's item worth lots of money. Carole could simply sell it, buy a more current (and more capable) keyboard, and have money to spare to pay for electricity.
This may be answered later, but maybe it was a gift she got when she was at the foster home, or she got it with her own money for cheap. Since it's portable and she seems to have had it for a long time, unless they give her a grand piano to perform on like in episode 2, it doesn't seem like Carole will be parting with her keyboard. It's like how Tuesday is so attached to her guitar, there's a stronger sentimentality there.
From a Doylist perspective, it's because Nord has a tie-up with the show. That said, her foldable keyboard is clearly something that doesn't yet exist today.
More on that keyboard?
What happened to Carole's keyboard during the talent show in episode 8? All we hear is Tuesday's guitar.
You can faintly hear Carole's keyboard playing in the back. She was probably playing lightly compared to Tuesday's guitar.
Non-Singing Language?
Why do they speak japanese but sings songs in english?
Artistic choice. Also, there is the Translation Convention entry in the main page. The characters are likely speaking English all the time, and the dialogue is being "translated" into Japanese for convenience.
It also helps to avoid the awkward Engrish that anime is known for, so they have the convenience of just having English speakers sing in English while the normal VA's speak in Japanese.
The characters are actually speaking 'Martian' in-universe, which is referenced a few times when one person pretends not to know the language. Whether 'Martian' is also supposed to be English or Japanese is another question.
Mermaid Sister Success
How did Mermaid Sisters even get onto Mars Brightest in the first place? They get very defensive when their Cluster F-Bomb lyrics are criticised, implying that they usually write their songs in that manner. Did they perform something less profane at their audition, or were they let in to be the token "entertainingly bad" act a la Jedward?
Maybe their last song did have profanities, but the amount was less than the one in "Galactic Mermaid". Alternatively the judges were asleep during their audition.
Or the executives knew their songs are offensive, so they purposely let them slide for shock value. They didn't need to move to the next round (and likely wouldn't be approved by the judges, anyway), they just needed something to grab attention. Just like how, in real life, "Galactic Mermaid" caught on with people outside of this show's fandom.
Consolation prize?
So despite not actually winning the Mars Brightest contest, Carole and Tuesday still get the chance to debut. What this entails is anybody's guess, though. They don't seem to get any recording time in a professional studio, nor do they get a producer assigned to them. Instead, we see them look for recording space and a producer themselves, which is exactly what they could have done anyway.
They were offered recording deals, but they declined because they risked compromising their creative freedom. And they could have skipped the tournament entirely, but people likely wouldn't have cared about them. Their viral video's fame was fleeting, only 10 people saw their performance in the cafe, and they couldn't finish their song at the Cydonia Festival. Not a lot of people would be interested in a bunch of nobodies, they needed to prove themselves.
Mars Years
How old is Tuesday actually? Years in Mars are twice as long as in Earth which means if she and Carole are stated to be both 17, but since Carole is from Earth Tuesday would actually be 34 in Earth years since she's a native Martian, however it's not really specified if Mars is measuring it's time by Earth years, so?
This troper suspects that Mars dwellers use Earth years, for sake of convenience (having matching holidays etc, as seen with Christmas and New Year). As time passes similarly in both Earth and Mars, and the girls definitely look more like 17 than 34, it is quite safe to assume that they both are indeed 17 Earth years old. A 17-Mars-year-old is the same thing than a 34-Earth-year-old.
Perhaps Mars years kind of work like leap years? I'd probably go with that.
Wrong Aide
Why did Valerie allow Spencer to aide her in her presidential campaign? She should have known that he helped Tuesday escape and run away in Episode 12. I would've expected her to disown her son for that high level of a betrayal.
Spencer's her favorite kid, to such a degree that she might be more forgivin' towards his betrayal. Also, PR—Disowning her son could sink her campaigne, though she could have done that privately.
Shouldn't she not know that?
How does Carole know that her birth father has a burn on his forearm? Her father was in jail when she was left to a church as a baby, so it is unlikely she remembers him nor that her church caretakers saw him. Did her mother tell the caretakers, if so, why? Now this seems to serve just as plot convenience to show the audience that Dann is Carole's birth father.
Three explanations:
No Infantile Amnesia: She might have recalled a glimpse of him in what limited memories she did have. She may have been dropped off at the church after seeing him (and we don't know exactly when in her infancy she was plopped at the church.
Alternatively, she may have been dropped off with a picture of her parents and got a hold of a records after aged out.
A third possible explanation is that she was only raised in the church when she was baby but her mother or some relative came back.
