On the cover, notice that the medallion worn by Alexander in his Richard III costume has the NSEA logo on it. The costume itself appears to be based on that which is depicted in the painting David Garrick as Richard III by William Hogarth in 1745. Even the medallion is present, though not with the NSEA logo! The David Garrick of the painting was an actor who portrayed the king in a 1741 production of the Shakespeare play.    A couple of flying saucers and a bunch of weird aliens, including a Gorignak, appear on the cover; they do not appear in the story itself.
Alexander as Dr. Lazarus as Richard III	David Garrick as Richard III by William Hogarth

On page 2, Alexander is depicted performing his fifth curtain call as Richard III. In Galaxy Quest, he comments lamentably that he used to give five curtain calls at the end of Richard III for his performance of that character.

On page 3, Alexander mentions a review in TV Guide that insisted he was the reason to watch Galaxy Quest. TV Guide is a bi-weekly magazine of television listings and related articles.

On page 4, Nesmith seems to state that there were 85 episodes of Galaxy Quest. But Guy states at the convention in Galaxy Quest that there were 92. Since Nesmith is telling the audience at the play of Richard III about Alexander's role as Dr. Lazarus at the time, it's possible he is referring to the number of episodes Alexander appeared in, not the total number of GQ episodes produced.

On page 7, panel 4, Alexander wields a Targathian pulse rifle. Targathians were mentioned in an episode of GQ as Nesmith flicks through TV channels in Galaxy Quest.

Oddly, it seems as if the Judgementites are entirely female. Hot females. 

On page 10, panel 1, notice that one of the holographic images of the Judgementites (the one on the far right) appears to depict a couple of ships in the sky in the background which look very similar to the Enterprise/Federation chevron emblem from Star Trek.

On page 12, Nesmith claims to the Judgementites to speak for the six trillion humans of Earth. Actually, at the time of this story, there were about 6 billion humans on the planet, not trillion. Of course, Nesmith always has been a bit full of it. (As of this writing, June 2013, a little more than 7 billion people live on Earth.)

Nesmith's stirring speech is an homage to many such delivered by Captain Kirk in the original Star Trek TV series.

Page 20 appears to show a number of flatscreen televisions in the store window though they were not widely available to the public until the late 2000's (this story takes place in 1999). 

Unanswered Questions

What was causing the faults in the Judgement Ship on pages 15-16? It's not entirely clear, though I assume that Nesmith's speech and the actor/crew's behavior were affecting the confidence of the Judgementites and thus diminishing their power.

Did Galaxy Quest: The Journey Continues get picked up for additional episodes beyond the pilot? (Note: Apparently it did, with the new title Galaxy Quest: The Continuing Adventures, according to the The Journey Continues comic book mini-series that followed in 2015.)

Will Alexander still want his character of Dr. Lazarus to die during the first season of the new series (as seen in "Destiny Be Mine!") so he won't have to continue the role? (Note: Alexander seems to have continued his role beyond the first season, as depicted in the The Journey Continues comic book mini-series that followed in 2015.)