- Ascended Fanon: Bandai has acknowleged fan attempts to mount all three weapon systems on the Strike Gundam at once, by releasing this. It became more official in the HD Rendition under the name of Perfect Strike Gundam, complete with a Robot Spirits figure and model kit for both 1/144 HG and 1/100 MG scales.
- Author Existence Failure: The Gundam Seed movie is likely to be placed on indefinite hold (if not outright cancelled) following Chiaki Morosawa's death from an aortic dissection on February 2016.
- Celebrity Voice Actor: Kira's voice actor, Matt Hill, is probably more famous for his athletic accomplishments as a 7 Time Iron Man Triathlon finisher, and a Co-Founder of the 'Run For One Planet' legacy.
- Also, T.M.Revolution performed the voice of Miguel Aiman, while Taiwanese singer Vivian Hsu (of the 2nd opening) was the voice of Aisha in the show's original run.
- Channel Hop: Gundam SEED was the first Gundam show to air on Tokyo Broadcasting System, and is the fourth network to air a Gundam show (after Nagoya TV [Mobile Suit Gundam, Mobile Suit Zeta Gundam, Mobile Suit Gundam ZZ], TV Asahi [Mobile Suit Victory Gundam, Mobile Fighter G Gundam, Mobile Suit Gundam Wing, After War Gundam X], and Fuji TV [Turn A Gundam]).
- Creator's Favorite: Kira Yamato and Lacus Clyne. Director Mitsuo Fukuda admitted that they're stand-ins for him and his wife, Chiaki Morosawa (who is also one of the head writers of the show).
- Enforced Method Acting: For the English dub, Matt Hill was kicked in the groin by James Corrigall, SEED's voice director, in order to make Kira's crying scenes more believable.
- Fan Nickname: Clotho, Orga, and Shani are called "The Druggies" for their dependence on drugs to perform at their peak.
- Milestone Celebration: The HD Remaster was released to celebrate the 10th anniversary of the show.
- Name's the Same: There was a "Freedom Gundam" in the prequel manga for G Gundam, "Mobile Fighter G Gundam: 7th Fight"
- Non-Singing Voice: In the English versions, Chantal Strand did her dialogue but Jillian Michaels was Lacus's singing voice.
- The Other Darrin: Romi Park replaced Mami Matsui as the voice of Nicol Amalfi for the Compilation Movies, due to Matsui being retired from voice work at the time.
- For the English version of the HD Remaster, NYAV Post will be redubbing the series, alongside Gundam SEED Destiny.
- Relationship Voice Actor: Like Zechs and Noin from Mobile Suit Gundam Wing, Brian Drummond and Saffron Henderson are a couple again as Andy and Aisha.
- Real-Life Relative: In the original English dubbed version, Samuel Vincent and his younger brother, Gabe Khouth, played Athrun and Nicol, respectively.
- Screwed by the Network: The anime suffered this on Cartoon Network. Originally aired at 10:30PM on Toonami with decent advertising, but its low ratings caused it to be shafted to a non-Toonami slot at 1:00AM on Fridays without much, if any, warning.
- Talking to Herself: Houko Kuwashima when Natarle and Flay meet in the Dominion.
- What Could Have Been: The original script called for the Strike Rouge to be built by the Earth Alliance instead of Orb, with Azrael placing Flay as its pilot due to her hatred of Coordinators and hoping to use her position as a Fallen Princess to stir up pro Alliance sentiment.
- Another rejected concept for the ending involved Azrael sending Flay back to the Archangel with a bomb implanted inside her, and her and Sai dying outside the ship in order to spare the others.
- Also in the same interview, Kira was originally going to be killed off, and Athrun would lose an arm in the final episode.
- Another idea for the ending would be an ending that was even more of an Kill 'Em All styled ending than the actual ending, with Athrun (while still being maimed in this version as well) apparently being the only surviving member of the main cast. Unlike the other examples, evidence from both the show and interviews suggests that this was indeed going to be the ending of the series and only was averted because the voice actors got too attached to their characters and the immense popularity of the Seed characters among the viewers.
- Before settling with Gundam SEED, Fukuda thought of calling the series Gundam SIN. Since that would have never worked in the USA, it was quickly changed.
- Gundam SEED and the CE timeline have become mainstays in Super Robot Wars after Alpha 3, and are the main Gundam representative on handhelds when all Universal Century Gundams were excluded from the handheld games after Judgment. Gundam SEED also appears in the Gundam Vs Series, beginning with its own dedicated game Alliance vs. ZAFT and continuing on into the Crossover games.
Trivia / Mobile Suit Gundam SEED