This episodes introduces the "spheres" which would be become an important part of the Xindi/Delphic Expanse story-arc.

In both the original airing of the episode and the rerun on December 3, 2003, the series title in the opening credits is just "Enterprise". It was not changed to "Star Trek: Enterprise" in the rerun as it was for "The Xindi". Even the UPN squished closing credits still said just "Enterprise" on Dec. 3.

The sphere in this episode is reminiscent of a Dyson sphere as seen in The Next Generation episode, "Relics".

The Osaarian ship was USS Voyager with a different design.

This is the first time we see an Enterprise crewman die.