Beam Me Up, Scotty!: For some reason, the video games love to do this... but Heero never pulls apart the Twin Buster Rifles, fires, and starts spinning. Yes, it would be a wave of devastation, but by the time he gets Wing Zero he actually gives a damn about civilian casualties, and the Buster Rifles sure as HELL don't discriminate.
To clarify, that scene actually happens in the series, but Heero wasn't the one in the mecha at the time. In fact, all other 6 of the 7 people who pilot the Wing Zero execute this little trick, the odd one out of course being Heero.
Possibly a justified usage. In the video games, there is no risk of civilian casualties to speak of; it's giant robots only. And it is quite the powerful attack, so there's no reason for him NOT to do it. Just because his progression through the anime makes him more...Heeroic...it doesn't mean he wouldn't use the attack if he could get away with the whole "no innocents" thing.
Furthermore splitting the rifle and going to town simply isn't Heero's combat style, notably enough he only seems to fire the rifle when it counts.
Celebrity Voice Actor: Heero Yuy's Voice Actor, Mark Hildreth, is a well known T.V Actor and voice actor. Unfortunately, he hasn't been asked to return to the role (or, more likely, he doesn't want too) due to some reception issues.
Cross Dressing Voice: In Japan, Quatre was voiced by a woman. Pretty much averted in everywhere else expect for the Flippino dub and Taiwan dub. Also, Duo is voiced by a woman in the Taiwan dub.
Demand Overload: When the show first aired in the US on Cartoon Network, Bandai's supply of Wing model kits got exhausted.
What Could Have Been: In the original draft, episodes 27 and 28 would have been flashbacks, revealing important moments from the Gundam pilots' and Relena's pasts. Unfortunately, scheduling conflicts arose which lead to head writer Katsuyuki Sumisawa quitting the series. The episodes were turned into recap episodes, and the backstories were archived in the manga Episode Zero.
The designs of the Gundams went through some odd evolutions. Some versions of Wing don't even have wings, Sandrock at one point had an "eagle claw" similar to Shenlong's dragon fang, and Deathscythe and Heavyarms' "nationalities" were swapped, resulting in early Deathscythes with very European gothic elements. And Heavyarms was, at one point, a flamethrowing clown giant robotnote The "nationalities" element comes in here too, since the clown theme was changed to the US military, which yielded the Heavyarms we know and love. In his mecha design artbook, Kunio Okawara admits that he was still in a G Gundam mindset at the time (especially with Clowny-Arms) and had to get away from that before he could work in earnest.
A few character tidbits:
At various points in the production, Wufei was envisioned as Ethiopian rather than Chinese, and was actually a Newtype (with the power to Sense Evil); the latter one was nixed late enough in production that a few rare pieces of merchandise like pencilboards actually still list him as a Newtype. Additionally, it seems Wataru Takagi was originally cast to play Wufei before being replaced by Ryuzou Ishino; Takagi would turn up as the hero of next year's Gundam.
Everyone knows that Zechs is a Char Clone, but few know that Noin was originally envisioned as a Garma Clone. The only vestige of this in the final anime is the design of the Taurus, which was always intended to be her personal mobile suit, and was designed with the keywords "sleek" and "spiky" in mind.
Lady Une was originally conceived as a naive country girl who fell in love with Treize; additionally, Treize's early character designs made him look a lot like Gihren Zabi.
Word of God: Director Masashi Ikeda, in an interview with Animerica, said that he didn't intend on a romantic relationship between Heero and Relena because he thought that the political and symbolic relationships between the two were much more important. Yaoi Fangirls love to cite this interview as proof that Heero's gay, Quote Mining it (accidentally or intentionally) to remove the other things Ikeda said. Like the fact that he didn't intend on any romance (straight, gay, or whatever), or him saying that the lack of romance is because of his own inability to write "boy-girl romance", or him saying that that doesn't mean Heero and Relena will never ever become a couple (he even admitted he could see it happening somewhere down the line).
One episode features what has to be one of the single most savvy mooks in the history of the franchise. This particular mook, whom this troper seems to recall never even gets a name, comments that "Outer Space has a bad habit of sending menacing objects to Earth"...which summarizes, to some extent or another, not only Wing itself but the vast majority of Gundam series, both before and since.
Naoko Matsui explained her involvement in Wing in an interview for the Series Bible books: After Mobile Suit Gundam ZZnote where Matsui played Roux Louka wrapped, the staff asked her "Say, if Gundam is still going in ten years, would you be willing to come back?" Matsui replied "Sure, why not?" and the rest is history.