The same alien species being mentioned is hopefully not a Missing Planets (Adipose nursery world, etc) level of Arc. But I doubt it's the last we'll hear of that.
These ostensibly-human two racers (when they saw the first tent, I was convinced it was another Satellite 5/Game Station game-show thing, and wasn't too
far wrong) not having heard of humans/Earth put them (probably) well into the future°, so the falling/melting Tim Shaw could easily have provoked a cultural grudge-match of epic proportions in the time since his contemporary visit to Sheffield. - Assuming that these weren't inexplicable parallelly-developed humanoids to yet be so close to be without the need for breaking out the latex and make-up.
We know Tim came from "5000 galaxies away", or thereabouts, so we're not entirely sure where(/when) the failed attempt to zero in on the TARDIS reached out to with the same equipment and some slightly confused Timelord Knowhow. Or at least Doctor knowhow, having claimed and proven proficiency in transporter technology, e.g. with the Dalek Asylum.
Another likely arc-cue is the talking bandages/stranglers¹. I think it is their taunting of the Doctor that knocked her resolve to survive to the point where it became fragile at the end. Some of what they said to her might
relate to the as-yet unresolved issue of Gallifrey (though I hope not) and links to her ep1 acknowledgement that she 'lost' all her family a long time ago, perhaps.
Ryan: No good balancing on a bike, does not like ladders, has good FPS experience (even if it doesn't help much) and might be the non-Doctor repository of random useful knowledge.
have a loving family (father, certainly, and her sister just would like
her room, probably wouldn't kill her for it) so has more than just the tedious 'puppy-walking' phase of police-work to go back to (speaking of which, she's trusted to be the sole driver/oparator of a police patrol car. Maybe not qualified for full lone pursuits, but capable of more than the old-fashioned panda-cars…). So that revises my opinion.
Graham: Probably enjoying this the most? No job, back home, lost his love, has found more to life than he previously believed possible, even after
the chemo got him into remission. If the medpod gave him the Translator Implant (to see further use even after
the TARDIS can work its magic again?) and dealt with his exposure to vacuum (quicker than Ryan, though Ryan had
maybe still held his breath, and that's the wrong thing to do!) then could it have brought him even from the threat of its return? Or yet a plotpoint.
TARDIS: Not sure yet about the internal design. The external design is greener, amongst other things. Is it perhaps anything to do with (in-universe) homage to the actual Sheffield police-box
that was actually name-checked? Noting that while Classic Who TARDII tended to have internal doors divorced in design from the external doors (one always assumed an 'airlock' between the console room and the door that matched with the current/eternal external result of the chameleon circuit), and then NuWho had for a long while the inside of the door or inside of the main face with the door, now it's a full 3-sided-and-roof portico/porch 'add-on' to the inside. Interesting.
° Inconsistent with what we know about the End Of Time knowledge, among other less-far-future settings, unless it's in a relatively Dark Aged future/region where the ultimate origins of such obvious humaniforms is lost to most people, in an Asimovian Foundation Era sort of way.
¹ First impressions of them
is that they went after Mr Grumpy Paranoid Misanthropic Contestant, whateverhisnamewas, because of his SniperBot² injuries. A mix between the Black Spot of the pirate ship caper and the bandages of the Mummy On The Orient Express. I thought they might be targeting the injured, to help but misguidedly so. That they were 'sentient', viciously and obviously designed to taunt (except when their target was asleep and there was just one of them there?) didn't come out until later.
² How rubbish were they? If they were produced by the scientists who developed flesh-eating water and all the other horrors (I presume the poisoned air was just "background-level not particularly healthy, like a smog only without the particulates" dangerous, at least for the (short³) day that they were to suffer it) then they must have been a very basic attempt from the beginning of their development and/or hamstrung. Compare with the Raston Warrior Robot from the classic era! And the only one who got hit was the one who should have been best in a shooting-match. Call Of Duty excepted.
³ Potential plot point missed. The deadline was to reach the goal before the next day, I think, and then later we find the suns were setting quicker than they should, so that might
have introduced yet more urgency to the process. SFAIK, the night coming quicker was the only issue they had.