Ben BrowderBen Browder was considered for the role of Major Hayes.
In episode #3.8, {Twilight}, T'Pol tells the amnesiac Archer that they are "...on the fifth planet of the Ceti Alpha system." This is the same planet on which Captain Kirk left Khan Noonien Singh in [Star Trek] episode {Space Seed}. At that point, Ceti Alpha V is described as harsh and inhospitable but survivable. Despite the fact that the landscape seen through the windows in {Twilight} seems to be not only congenial but even pleasant, as opposed to merely survivable, this is consistent with what is learned of the Ceti Alpha system in Star Trek: The Wrath of Khan. In the film, Khan states that Ceti Alpha V was turned into a wasteland by the explosion of Ceti Alpha VI, which altered the orbit of Ceti Alpha V. Planets don't typically explode for no reason - it is likely that there was an ongoing problem with VI that turned V from the paradise we see in {Twilight}, to the "harsh but survivable" world described in {Space Seed}, to the wasteland seen and described in The Wrath of Khan.
Although produced in widescreen since 2001 in anticipation of HDTV, actual broadcast of the series in HDTV by UPN did not begin until the fall of 2003, midway through [season 3].
Julia RoseJulia Rose, who has a recurring role as a space marine (MACO) this season season, wears a uniform previously worn by [?] Hilary Swank in The Core. According to a September 2003 interview with Rose, the uniform still has a label with Swank's name on it.
The Enterprise's sister ship (the NX-02, seen under construction in the episode {The Expanse}) was finally given a name, Columbia, towards the end of the third season. The ship was named after the space shuttle Columbia, in honor of its late crew. This leads some to speculate that all NX-class ships will be named after space shuttles, because this is actually also the order in which the orbiter fleet was built. Enterprise came first, as a test vehicle not flown in space, then Columbia. In the order they were produced, the orbital vehicles (popularly known as spaceshuttles) made after the first two were Challenger, Discovery, Atlantis, and Endeavour (built to replace the loss of the Challenger). With NX-01 being Enterprise, NX-02 Columbia, it is within reason that NX-03 will be Challenger, NX-04 Discovery, NX-05 Atlantis, and NX-06 Endeavour.
T'Pol's eyebrows change appearance between the second and third seasons, becoming more arched and Vulcan-like. In a 2004 interview with Femme Fatales magazine, Jolene BlalockJolene Blalock revealed that she and her makeup artist unilaterally decided to sneak a change in T'Pol's eyebrows amongst the character's pre-third season hairstyle and costume alterations, and no one from the production office complained.
It is revealed in the season three finale episode #3.24, {Zero Hour}, that the founding members of the United Federation of Planets are Humans, Vulcans, Andorians and Tellarites.
Out of all the main Xindi characters, the Xindi-Humanoid (played by Tucker SmallwoodTucker Smallwood) was the only one whose real name we never learned.
