can i just say - the whole setup of this blue man shooting Bill because he’s so scared of the monsters coming up the lifts. WHY? a minute later he establishes that actually, they won’t harm him, they never have, and they would have taken Bill from the room, which would have had exactly the same effect (in essence) as shooting her - and then they would have left again. so that was stupid and doesn’t make sense.
then the cybermen coming up the lifts in the first place doesn’t make sense unless the Master deliberately shooed some cybermen up to fuck with the Doctor (also wow, did the Master spend like, a couple of thousand years down on this colony ship? why? (how old can he get?) i mean. yeah. he couldn’t escape the black hole, but why not commandeer the lifts and sit up in command to experience less time? anyway i don’t think it’s ever become clear to me why the crew going down decided to stay there and have some kids, the lifts did not seem to suffer any time dilation effects in a way that would have prevented them from stepping right back on and arriving back up a few seconds after they’d left - in fact i feel like the lifts should have had some time stuff about it, like calling them would take literal AGES downstairs, and they’d be almost instantly available upstairs (those lift numbers going extremely rapid but then slowing further and further down to ‘normal’ pace as it comes up to command)
EDIT: IN FACT they could have had Bill call the lift and made that a measure of the time dilation instead of the on-the-nose ‘days’ comparison.