The snow is actually explained in LoRS (very vaguely, but explained) as basically this.
“It was snowing the night that Ruby was born, and it keeps snowing all around her. Actual snow. Which means that that night is so raw and so open, the last thing that I should do is take a time machine back there.”
I mean, why would an ambulance identify someone from 3,000 years in the past as your next of kin?
And as for the cloak, maybe the specific cloak is a bit weird but it’s perfectly reasonable to think that a 15 year old who has hidden her pregnancy would wear something that hides her identity when she drops the baby off.
Maybe, but I think when you’ve come to a a conclusion, there is no mystery to Ruby! Her mum is just a normal person! Hammerd home the point about how great it is to be ordinary. & even give her character a satisfying ending, well for some, with her ‘new’ family as problematic as that is for me. Then you announce oh wait but she will be back & there IS some familial mystery to come. It’s like RTD wants it both ways.
It all comes down to enjoyment of course, as someone who didn’t enjoy this season I just found that final hint at things to come from RTD tiresome.
I’m subverting expectations folks & now I’m going to subvert the subverted expectations!
This is also true. Probably why I didn’t register it as a problem with the mystery and more as a dilemma for within that episode’s narrative.
Especially when you consider it’s a completely different planet…
Generally speaking, this is true.
In the case of reactions to this particular episode, I observed numerous responses such as, ‘I like it, but it was poorly/badly/very badly implemented.’
The responses were, at least often enough to register in my mind, along the lines of, ‘Ah, you don’t like this aspect!’ (which is not what was said), or ‘Just because your expectations were not met,’ and so on.
In my humble opinion, it’s just as uncool to speculate about the ‘true reasons’ why someone else doesn’t like something, as it is uncool to react aggressively simply because a speculation did not come true.
To end on a more positive note: live and let live.
My brain makes odd connections sometimes, and for some reason, this made me think of a small arc in the anime Hyouka. where a school club is filming a mystery, but the script they have incomplete, lacking the ending revealing who the killer is, and the script writer is in the hospital and not able to get them the actual ending.
We end up with both the ending our main character tells the club… and then a discussion of how that probably wasn’t the intended ending, and what it probably actually would have been.
I really should rewatch that sometime…
I may misremember it, but I thought it was explicitly stated in the episode that the ambulance should be able to do that.
Edit: And it seems I remembered incorrectly (Transcript for episode ‘Boom’ • Doctor Who · TARDIS Guide, searched for “next of kin”). Ruby was in its database but that does not mean all people from her time are. Really great to have transcripts, thanx @shauny .
I’ve read this elsewhere but I think it makes the most sense:
The snow is Sutekh manifesting himself. It always started snowing around Ruby when she was thinking about her mum, so that’s when Sutekh hopped in to play Sherlock Holmes. Maestro pointing out something ancient in Ruby was them partly recognizing Sutekh around her, and they mistook it for Ruby being funky. It’s also why it starts snowing around Mel when Sutekh takes over her.
Though no matter how much sense this makes, or sense any theory makes, I do kinda think i wouldn’t need tumblr to explain to me how things work because of how vague they kept it, but it’s a choice of making it more mysterious and open to interpretation. That’s fine. It’s not an objectively bad thing.
See, I have no problem with this because at that stage in the Doctor’s timeline, Ruby’s next of kin wasn’t known. I know consistency of time travel has always been… inconsistent in DW but this portrayal is, at least, in line with the growing block theory of time travel.
Now this I will happily give you. Even as a staunch defender of the episode, 'twas a little weird. 
Ah, but this was down to Sutekh, wasn’t it? From “The Legend of Ruby Sunday” the Doctor at one point says “…that night is so raw and so open, the last thing that I should do is take a time machine back there.” and, earlier, back in “The Devil’s Chord” it is “the one who waits” being present that chimes so deeply with Maestro. Specifically this exchange:
DOCTOR: Christmas. The music that was playing the night that she was born.
MAESTRO: How can a song have so much power? And power like him?
DOCTOR: Like who?
MAESTRO: The Oldest One. On the night of her birth. He can’t have been there. What for? What for? What for?
It’s Sutekh’s presence that causes the snow, the music. That point in time becomes like an open wound and things… bleed through.
Ah ok. Makes sense I guess.
Many thanks in return. Sometimes it is because we question that I get to see things a little more clearly myself. It’s why I enjoy these exchanges.
See, for me, when I hear the phrase “subvert expectations” I think of the Game of Thrones finale, which was infamous for setting up certain arcs throughout the season that led up to it just for the writers to change everything last minute because they didn’t like that the fans figured out the ending. I much prefer being able to tell what’s coming than having something surprise me. I don’t care about being surprised, I want the story to make sense! And while I fully had the speculation of Ruby’s mum being a normal human, I said time and again that it doesn’t work with the setup.
I feel like knowing “how RTD usually writes companions” shouldn’t factor into the speculation of a brand new story he himself has claimed is a soft reboot.
The fact that you have to say that really only proves to me that it was badly written.
You speak too much sense. Be careful, or people might actually start, you know, listening to you! 
I have a class of 8 and 9 year olds who rarely do that. I’ve not a hope with fandom!
I will very quickly chime in as one of the people accusing Russell of lazy writing - I am accusing him of this because I am a writer, and I have written lazily in the past when I have realized by deadline is approaching and the cool thing I wanted to do just isn’t going to come off in time so I have to patch something over. Sometimes, that’s three pages of a game of catch. Sometimes, that’s “Oh, she wasn’t ever anyone special we just made her special with our thoughts” couched up in a tonne of vague language. Sometimes, it’s a big Disney dusting scene and some emotional screaming that can take us away from the finer details of the script’s inefficiencies.
When I say “lazy writing”, I don’t mean that he doesn’t want to write. I’m pretty sure he wants to write more than anything. When I say “lazy writing”, I mean that he basically went with the simplest route that he possibly could to resolve the story that he was telling, without any regard to what he had been working on up until that point, it seems. They find both her biological parents, turns out she wasn’t really that special anyway, it’s all resolved in a neat and tidy bow that doesn’t really have anything to say, but what does it do? It gets your arc resolved. It gets you to next season. It keeps fans wondering who the fudge Mrs. Flood is. It does all the things you need it to do at the barest possible level, but for me, there is no craft at play in LoRS/EoD in the same way that say, 73 Yards employed the craft of writing.
73 Yards was art. This finale was an exercise in narrative box ticking. That’s why I feel justified in calling it lazy, because it has happened with Russ multiple times before. I don’t think expecting something new from someone who has been talking all year about how this is revolutionary new Who we’re doing is too much.
Agree 100%. As I’m watching the 2005 season I can really see how much worse RTDs writing has got.
& Mrs. Flood, total cringe tbh. How does RTD keep mentioning her. She just breaks the 4th wall & talks to the audience! Lazy!
I think the biggest giveaway for me is that Russell claimed Dot And Bubble/73 Yards (I can’t remember which but it’s one of them) as the greatest script he’s ever written, and I buy that. It shows in those episodes.
The finale gave me vibes that extend no further than someone going “Yeah, that’ll do.”