On page 1 of the story, the incoming UFO is depicted flying an odd, zigzag course through space. This is similar to the actions of the UFO at the beginning of "E.S.P.", though the story proceeds quite differently from there.

Panel 7 of pages 2-3 seems to show blue sky and clouds outside of the cockpit of Foster's Interceptor, yet they are chasing the UFO through space, not atmosphere, as all other panels clearly show.

In this story, we see a new type of alien craft, never seen before. The new ship also has a tractor beam and is large enough to have its own landing bay with room for several standard UFOs and Foster's Interceptor.

After being captured by the alien craft, Foster finds himself wearing one of the alien spacesuits, complete with a liquid-breathing environment to protect him from the acceleration of the craft. Oddly, the fluid he breathes is not green like that of the aliens; it must be a different formulation for his human body. (Recall that Foster was earlier subjected to the fluid-immersion suit in his dream in "Ordeal").

The aliens who have captured Foster are able to speak English to him, unlike the aliens seen in previous stories (with the exception of a possible turncoat alien in "Arctic Affair".

This story reveals that the aliens not only wear the pressure suits for space travel, they also place themselves in suspended animation for the majority of the journey between their planet and Earth, which takes "many Earth days". Here, Foster is also forced into suspension within a pressure suit for the trip to the aliens' homeworld, described as being on the edge of the galaxy. There is no indication that Foster and the other humans who escape from there at the end of the story know where the planet was at though, so could not report it to SHADO upon their return. 

This story reveals that nearly every one of the aliens is a physician or space scientist, the two occupations that are their species' only hope for survival. The planet is said to be made up of hospital cities. Notice the city here appears to be the same one seen in the chronologically-earlier but later-published "Shock-Wave" (though a normal-looking blue sky is seen here instead of the odd background seen in "Shock-Wave") and the story following this one, "The Renegade".
Scene from "Shock-Wave"	Scene from "Homeworld"	Scene from "The Renegade"

Arriving on the alien world, Foster's two abductors warn him not to remove his helmet, for he would not be able to breathe in their atmosphere. Before long, he is shot with a drug that does allow him to survive without a helmet for a time. In the past, when the aliens have landed on Earth, they are able to breathe for a short time without a helmet before succumbing to something in the atmosphere that fiercely accelerates the aging process of their bodies, causing their death.

The only alien named in the story is called Robart.

All of the aliens seen on their homeworld are green, even though it's been shown that the green tint of their faces when seen on Earth is from staining by the green fluid of the pressure suits. On the homeworld, you'd think that most of them had not recently undergone space travel where they'd have picked up the coloration. Even Robart has a green face (except in two panels, where he's first seen, in which he has Caucasian-like skin coloring). 

On panel 14 of pages 12-13 of the story, the female Moonbase operative appears to have a brown wig on instead of the traditional purple. Also on pages 12-13, Straker is depicted with yellowish-blond hair instead of platinum.

UNANSWERED QUESTIONS

How are Foster, Dinkler, and Shaffer able to pilot the UFOs they use to escape from the alien world? Thus far, SHADO has not been able to capture one intact for study! And even if Foster somehow knew how to do it, how would he have time to instruct the two doctors in their own UFOs? Possibly, the UFOs stolen by Foster and the others were preprogrammed to head to Earth, since it seems unlikely there were any English instructions of how do it or even how to get to Earth from their distant location.