En route to meet with the Xindi Council, Enterprise comes across an alternate version of itself.
- Actually Pretty Funny: Lorian cracks a smile when Trip comments that his ears obviously came from his mother.
- Antagonistic Offspring: Lorian, son of Trip and T'Pol, briefly becomes this.
- Apologetic Attacker: Lorian apologizes to Trip before stunning him.
- Call-Back: Throughout the season, the Xindi wonder how many human ships are in the Expanse. Degra even tells Jannar "those readings were never confirmed." Turns out, they were right.
- Combat Pragmatist: Outgunned, Archer resorts to using the transporter to beam away the alternate Enterprise's power systems.
- Fearful Symmetry: Enterprise vs Enterprise.
- Half-Human Hybrid: Lorian, Karyn Archer, and lots of Phlox's descendants.
- Heroic Sacrifice: The alternate NX-01 stays behind to cover Enterprise into the subspace corridor. Whether they were destroyed or the successful trip negated their existence is anyone's guess.
- My Greatest Failure: Lorian failed to stop the Xindi when he had the chance.
- No Time to Explain: Lorian, when he first tells Archer to reverse course away from the nebula.
- Our Wormholes Are Different: This one gives Enterprise the Timey-Wimey Ball the first time through.
- Ramming Always Works: Lorian's last-ditch plan to stop the probe, except that he hesitated to carry it out.
- Rescue Romance: Heavily Implied by Karyn when she tells Archer that his future wife is someone who he rescues from an anomaly field.
- Theme Naming: It's revealed that the NX-02 was named Columbia. The novels confirmed that all of the NX-class were named for America's space shuttles.
- Time-Travel Tense Trouble: Phlox experiences this when telling Archer how, according to Lorian, he discovered—or will discover—a way to combine human and Vulcan DNA.
- The Un-Reveal: Hoshi learns that she had two children on the alternate NX-01, but she chooses not to find out who the father was.
- Villain Has a Point: Mallora reasonably points out that the humans could have manufactured their "evidence."
- Well-Intentioned Extremist: Lorian, if not outright Hero Antagonist.
- Whole Plot Reference: It's very much a reuse of DS9's "Children of Time."
