One of Metal Sonic's lines during the final battle has a typo. He says "But that's was the past. Now you're nothing but a speck of dust to me." The line is spoken correctly, so the subtitles don't match. The infamous "Look at all those Eggman's robots!" from Tails suffers from a similar problem.
In the September 2003 prototype, Sonic's eyes are colored blue on the title screen.
Children Voicing Children: William Corkery, the voice of Tails, was about 10 when he recorded his lines, making him one of the youngest English VAs in series history, if not the youngest. His sister Emily, who voiced Charmy, was around 13 at the time of recording.
Creator-Driven Successor: To Knuckles Chaotix in some ways. Not only does Heroes reintroduce the Chaotix characters themselves, it is also the first major game in the series since Chaotix to feature a teamwork-style multi-character gameplay dynamic. And of course, it is the first game after Chaotix to feature Metal Sonic as a primary antagonist and involve a One-Winged Angel form of them as the Final Boss.
Creator's Favorite Episode: According to Jun Senoue, the theme for Seaside Hill was his favorite song to compose for the OST. Additionally, "What I'm Made Of" (the theme of the True Final Boss) is one of his favorite Crush 40 songs, as well as the Crush 40 song he and lead vocalist Johnny Gioeli enjoy performing the most.
Keep Circulating the Tapes: Outside of a re-release on PlayStation Network in Europe and Japan, the game hasn't been ported elsewhere on other consoles and its 2004 Windows port is considered abandonware for many years. On the flipside, the game is backwards compatible on Wii and Xbox 360 (but unfortunately not on Xbox One and Xbox Series X|S), and secondhand copies are floating around for a reasonable price.
Kids' Meal Toy: In late 2004, McDonald's released a set of eight LCD games in the US. The first seven featured one or two characters from the game (Sonic, Tails, Knuckles, Amy and Rouge, Shadow and Omega, Cream, and Big), but the eighth one was based on Billy Hatcher and the Giant Egg. Pakistan received a slightly different promotion, this one featuring six LCD games (Sonic, Tails, Knuckles, Amy and Rouge, Shadow, and Cream).
After Shun Yashiro's death the same year Heroes was being produced, Takashi Nagasako took over as Big the Cat from this game on.
The role of Tails went from Connor Bringas, who voiced the character in Sonic Adventure 2, to William Corkery. note As with Bringas taking over for his older brother Corey (who voiced Tails in Adventure and Shuffle), this is presumably due to Bringas' voice being too deep to perform the role; he was already 13 when SA2 was released for the Dreamcast and would've been in his mid-teens when Heroes went into production. In the Japanese version, his Sonic X seiyuu Ryō Hirohashi takes over from Atsuki Murata and has voiced him ever since.
Real-Life Relative: The Corkery family all voice different characters in English: son William voices Tails, while his father Bill and sister Emily respectively voice Chaotix members Espio and Charmy.
Stillborn Franchise: Sonic Heroes was actually created to be a new independent Spin-Off franchise for the Sonic series much like the Sonic Adventure games... but a weak PlayStation 2 port and a lack of support put a quick end to any ideas of following up with a sequel.
This was Sega's first attempt to make a multi-platform release and they were working with a new game engine to boot, so textures and lighting were cut back to the bare minimum so the graphics would render properly across the Xbox, GameCube, and PlayStation 2.
The game had only two level designers, one of whom became sick and passed all of his duties to Takashi Iizuka, who was forced to create the last few levels entirely by himself. The resulting crunch led to Iizuka losing 20 pounds just to finish the game on time.
The game was going to be Sonic Adventure 3, but the idea was scrapped to not lure away or confuse newcomers of the franchise when they decided to port the games to new consoles.
Final Fortress was originally conceptualized◊ as a massive Underwater Base before being changed to a Cool Airship in the final game. The Final Fortress and the surrounding ships being aquatic-themed is a likely nod to this idea.
One Zone that seemingly never made it past the concept art stage was a pirate-themed Zone.◊ The idea would be revisited and realized for Sonic and the Secret Rings as Pirate Storm. The lack of Knuckles and Tails in the concept art also heavily implies that Heroes was originally planned to have one character playable in a Zone as per previous titles as opposed to three at once.
In 2018, the director of the game, Shiro Maekawa, tweeted the initial plan and roster. Team Sonic and Team Chaotix are identical to the final product, but Rouge was on the same team as Amy and Cream, Big was allied with Chaos and a rebuilt E-102 Gamma, and Heroes would have marked the first appearance of Fang, Bark, Bean, Mighty, and Ray in the modern era, the latter two being on the same team as Metal Sonic. Omega was likely a replacement for Gamma, and Shadow's resurrection was not planned at the time. Ironically, the team of Fang, Bean, and Bark would later be made into Ascended Fanon much later through the work of Ian Flynn as the Hooligans, well before Maekawa revealed this intent to have been a thing at all.
In 2023, an early script for Heroes got into the hands of fans, revealing that Robot Carnival and Robot Storm were going to be "Egg Hermit Crab" and an "Egg Sea Anemone", respectively, and that the Egg Emperor was going to be "Egg Mobile Force." It also mentions a Christmas mountain-themed level in place of Lost Jungle.
Other trivia
In early prototypes of the game, Jon St. John doesn't have any filters applied to his voice. Because of this, Omega speaks with a monotone human-like voice. Most stages are also missing their music in early prototypes.
The Nintendo GameCube version was released a few weeks early in North America.
the theme for Seaside Hill was his favorite song to compose for the OST. Additionally, "What I'm Made Of" (the theme of the True Final Boss) is one of his favorite Crush 40 songs, as well as the Crush 40 song he and lead vocalist Johnny Gioeli enjoy performing the most.
