Franchise Killer: While it had been on the wane since Battle Network 4, the overwhelming mediocrity of Star Force 2 ended the popularity of the EXE verse, the last popular Mega Man series, in Japan. They got their act together for the third installment, but sales didn't perk up. Not much funding at all was allocated to Operation Shooting Star, an attempt to uncancel both series that might have worked if it were a proper remake. A sad fate for the franchise that had its iteration of Mega Man as the face of its 20th anniversary.
No Export for You: It looks like this is going to be the fate for the Star Force/Battle Network crossover. No real loss though.
Also the Lunar Knights link features in Star Force. And the Wave Command cards in the European version of Star Force 2. And the Noise Mod Gear cards in the non-Japanese versions of Star Force 3, yet they were mentioned on the North American version site.
The names of each of the zodiac bosses, their designs, and even the concept of astronomy-based foes actually comes from a Chinese only game called Rockman Strategy. Taurus, Cancer, Libra, and Apollo share very similar designs with this game. While big and covered in red armor in both games, Strategy!Taurus actually had his proper zodiacal element of Soil (compared to Taurus Fire's, er, Fire); both Cancers were naturally water-based; Strategy!Libra had the Wind element (Libra Balance is Non-Elemental boss that uses both water and fire attacks, and has an informal association with the Break attribute, rather than Wind); Apollo Flame and Strategy!Apollo are so similar in design you could argue that the first is an Expy. No link between the moon god Luna of Strategy and Miss Platz, though.
What Could Have Been: Star Force 4 was in the works, but they were informed they had to wrap the games up with 3, leading to the ending.
In the second game, we could've had a Pirate and Angel tribe.
And a noise form based off of Harp Note in the third game, also some of the noise forms were to have the old Megabuster from the first two games.
According to earlier statements by Xebec, the Tribe anime was meant to have 55 episodes, same as the first season. Concept art of the anime includes images of Apollon Flame and General Auriga, suggesting the anime was originally planned to have arcs including them.
Some of the earliest designs for the character who eventually became Ace set him up as another superpowered individual on Geo's and Solo's level, but who was more of a hooligan than anything else and with vague connections to Dealer. Concept art shows him rescuing Luna and getting under Solo's skin. Also notable was that his EM human form was largely an imitation of Mega Man's appearance.
Before she became the Emotionless Girl we all know, Tia once had a perkier nature.