Q's cameo in The Stinger and his conversation with Jack re-contextualizes much of Season Two and Q's role there. Since this Q comes from a temporal point prior to his death (and seems to be aware its coming), the implication is that by helping Mon Capitaine come to terms with his family history — and especially the specters of Maurice and Yvette and how Picard didn't want to become a parent — Q knew what awaited Picard in Season Three. Q was trying to help prepare his favorite mortal for encountering his son, accepting Jack, and realizing neither of them have to be alone — all lessons and self-acceptance that pays off in the series climax here as the key to both Picards breaking free from the Borg for good.
This also further ratifies him being a Trickster Mentor to Picard more than the Captain ever realized, as Q's decisions in Season Two were effectively there to help teach Picard how to finally overcome the trial he put him on all those years ago back during their first encounter back at Farpoint: to open his mind to possibility, and in this case, the possibility of accepting oneself, in spite of all one's faults, fears, and traumas, and finally make the connections he was sorely lacking his entire life. Even introducing him to the Borg in the first place can be seen as an extension of this, as for all of the Borg's talk about being one voice and feeling connections that no others could understand, the Power of Love overcoming their assimilation proves that the Borg Collective never understood anything about empathy and are effectively powerless before it as Jack rips himself out to save his father, a possibility only possible thanks to Q's hand in leading Picard down this path.
Alice Krige was 43 during filming of Star Trek: First Contact and 67 when she provided the voice of the Borg Queen in Season Three. She makes no attempt to sound younger in order to replicate her earlier portrayal, and the older voice fits with the visuals of the run-down, barely holding on character.
By leaking Raffi's classified intelligence file, it has ensured that she can never work undercover again. Which means she can now take a regular non-intelligence posting.
Imagine how much worse Sidney's tearful breakdown would have been if she had been deassimilated after shooting Seven of Nine. Additionally, Picard earlier mentioned that while assimilated, 'I felt an intense euphoria but no sense of my existence'. So Sidney is not only horrified that the Borg forced her to kill people she cared about and could do nothing about it. She's also horrified that they forced her to enjoy it.
Seven of Nine is now the Captain of the Enterprise-G. Now, G is what number letter in the alphabet? The seventh. And if you take into account the NX-01 and Kirk's Enterprise, the Enterprise-G is the ninth Starfleet vessel to bear that name.
As an ex-Borg being made captain of the Enterprise-D's successor, with Picard's son as her counselor no less, any doubts of Seven's allegiance is gone.
One of Picard's first lines back in "Remembrance", when he was playing poker with the dream facsimile of Data, was, "I don't want the game to end." And in a way, fittingly, now it never will. Our final glimpse of Picard and the TNG crew all together, as they exit the franchise and head off into the TV afterlife, is them playing the game forevermore.
Considering how badly the Enterprise-D did against a Borg cube in its only other encounters, it's pretty shocking that it was able to not only hold out against, but annihilate the new cube, even with how crippled said cube is...until you consider that it isn't really the old D making that possible. It's the Syracuse and its Dominion War-era stardrive, a stardrive built with the latest Starfleet weapons and engines technology of the time and designed to fight both the Borg and the Dominion. Galaxy-class ships were shown to be some of the most prolific warships of the era, an era of combat influenced heavily by the Lightning BruiserDefiant-class.
Fans have studied footage from TNG and noticed that the saucer section has different phaser banks now. Geordi sourced Dominion War-era phasers when restoring the saucer section.
Borg cubes have previously been shown to suffer from Imperial Stormtrooper Marksmanship Academy if their drone "crew" complement is depleted. The VOY episode "Collective" showed a Borg cube where a mysterious calamity had killed most of the drones aboard, leaving only a half dozen "teenagers" (assimilated children that were in the process of Rapid Aging in the Borg's maturation chambers when the calamity struck) behind. When Voyager encountered this cube, they took almost no damage whatsoever.
Some Fridge Horror for the aftermath of the assimilation: nearly every Starfleet officer on those ships over the age of 25 was likely killed as well as the crew of the space dock. Starfleet will need years to rebuild its professional manpower. May also be a factor in Jack being commissioned so quickly.
