Let's talk about assimilation.
The way The Borg assimilate new species into the collective changed over the years. When an away team from the Enterprise-D first boarded a Borg cube (after being thrown halfway across the galaxy by Q in an attempt to prove to Picard that humanity was becoming too cocky for its own good) they discovered a Borg hatchery of sorts - an infant already upgraded by Borg technology. Data surmised that Borg were born biologically and that implants were added shortly after birth. Picard's capture in The Best of Both Worlds seemed to corroborate this - we watch as Picard is transformed into Locutus one implant at a time.
Borg reproduction wasn't an issue for the rest of the television run of the Next Generation, but First Contact changed things considerably. Now, assimilation could be done 'on the fly' as it were - nanotubules could be extended from the backs of the hands of Borg drones and used to infect desirable life forms with nanites that would start to reconfigure their bodies from the inside out.
This method was far more brutal and much, much faster than the old slice 'n dice method - prospective drones could be brought into The Collective in bulk. It has its downsides, however - this instant assimilation method is what allowed Captain Janeway to infect the Borg Queen with a virus that caused her to lose enough control over the collective that Voyager managed to get itself home.
It's also interesting to note that the Borg sphere stranded on 21st century Earth during the events of First Contact contained Borg of the later, instant assimilation type - although they are chronological predecessors to the initial assimilation method, those specific Borg came from a post Next-Gen world and their methods match. Knowing the production staff's willful ignorance of certain elements of trek history, I think it's a bit of a stretch that they intentionally got this little tidbit right.