On page 2, we see the drilling platform dangling from Nero's mining ship, the Narada, that will later be assimilated as part of the Romulan/Borg ship also called Narada in the 2009 Star Trek movie (beginning with the "Rebirth" study here on PopApostle).

Page 7 reveals that a new level of tolerance and curiosity in Romulan society has allowed Spock-Prime to make a legal residence on Romulus in the 24th Century and page 8 reveals he has done so for the past 5 years (though he lived there illegally as an underground peace ambassador for 15 years before that; the line on page 5 stating that he lived there for 40 years is inaccurate according to the official timeline and it was corrected to 20 years in the trade paperback collection of the mini-series).

On page 8, Ambassador Spock opens his comments to the Romulan Senate with, "Friends, Romulans, countrymen...we share the same ears." This is a humorous reference on Spock's part to the first line of a famous speech made by Mark Antony in William Shakespeare's play Julius Caesar. The actual line goes, "Friends, Romans, countrymen, lend me your ears." The Romulan senators and spectators laugh at Spock's joke, presumably only for the remark about the pointed ears of Vulcans and Romulans; it seems unlikely they would be familiar with Earth's Shakespeare (or the Klingons' for that matter).

On page 9, Spock mentions the rare isotope decalithium. This may be a relative of dilithium, an element in the hypersonic series of elements according to Star Trek lore; di- means two and deca- means ten. The Vulcan Science Academy later processes decalithium into so-called "red matter". All of these are fictional substances.

On page 12, Spock warns Nero that his plan would result in him being sentenced to life on a prison planet if he were caught by the Empire. Although this doesn't happen in the course of Countdown, Nero is, ironically, sentenced to life imprisonment on the Klingon prison planet of Rura Penthe as a prisoner of war in "Second Chance".

On page 13, Spock is somehow able to view the growing supernova in "real time" through his telescope despite being, presumably, light-years away at his home on Romulus. It must be some kind of subspace-telescope capable of fetching live images from across space!

Page 16 reveals that Spock is the Federation ambassador to Romulus, while another Vulcan, Sular, is the Vulcan ambassador to Romulus.

Notice that, on page 18, when three unidentified vessels warp into orbit around the planet in the Kimben system, Spock vanishes from behind Nero's shoulder on the bridge of the Narada from panel 2 to panel 3. Presumably, he wouldn't want to be seen on the communications screen should the unidentified ships make contact, as the presence of the Federation ambassador to Romulus aboard a Romulan mining ship would raise some eyebrows.

The unidentified ships are revealed to be Reman vessels. The Remans are the inhabitants of the secondary planet called Remus, sharing the orbit of Romulus. The dual worlds were named, in human annals, after the mythological twins who founded Rome, Romulus and Remus, in ancient Earth history.

Notice that panel two of page 21 reuses the same figures of Spock and Nero seen on page 19, panel 3.

On the last page of this issue, Data appears as the captain of the Enterprise-E. Data was supposedly destroyed in a starship explosion in the 2002 film Star Trek: Nemesis. "Countdown" Part 2 reveals that Data had successfully loaded his programming into the earlier prototype android called B-4, who was also modeled after its creator, Dr. Noonien Soong, as was Data. When Geordi La Forge later installed Data's emotion chip into B-4, the android was finally able to fully access all of Data's memories at the time of upload and essentially became Data, eventually earning the command position aboard the Enterprise.