Creator Killer: Good luck finding anyone who has positive things to say about Yoshio Sakamoto after he made this game.
Executive Meddling: Sakamoto was not a particularly good director to work with. He was responsible for the whole story and nearly every aspect of production, with Team Ninja only doing the grunt work (and they weren't allowed to do their signature style of Fanservice-although there are a lot of bum shots since Sakomoto shot down everything else). The Wii Remote-only control scheme was not only his idea, but he actively insisted that this scheme was to be used exclusively, which was frequently questioned by Team Ninja employees who wanted to employ the Nunchuk. He even noticed problems with the control scheme, but kept it anyway because changing it would be "admitting defeat". There was also one part where he forced the composer to make a piano piece... in a matter of a day. He was also responsible for the American localization, directing the voice actors despite not being an English speaker.
Mysterious Black Dude, Remember Me Guy, or Manthony for Anthony Higgs.
BSL (Blonde Scientist Lady or BOTTLE SHIP Lady) for the important woman at the end of the trailer (Who's apparently named MB). Interestingly and coincidentally, this happens to be the same name as the space station that is the setting for Metroid Fusion.
"El Pollo Loco" for the Mystery Creature AKA the chicken lizard◊...thing which turns out to be adolescent Ridley.
Ridley's infant form is a creature◊ that looks like either a furby with legs, or a cross between a Chocobo and a Moogle. Fans have nicknamed him "Choogle" or "Choogu". It also has an in-universe nickname: Little Birdie.
After both creatures were revealed to be forms of Ridley, Little Birdie and the Mystery Creature were given Punny Names by the fans, which are Furbley and Ugley respectively.
Ridley himself is affectionately called "Roidley" because of his sudden change in bulk compared to previous games, where he was skinny as a rail.
Franchise Killer: It took four years for another game to even enter the planning stages.
I Knew It: Did anyone really believe that Ridley was dead for good?
Magnum Opus Dissonance: Yoshio Sakamoto wrote the story so it would be the best title in the franchise from the narrative perspective and to make Samus a truly developed, rounded and sympathetic character. It was stated in interviews that he even cried when he saw some of the scenes of the game for the first time, showing how emotionally invested he was in the project. The result was the most vilified entry in the entire series (many fans like to pretend it doesn't exist) and one of the biggest Internet Backdraft in video game history due to the perceived Badass Decay of Samus. Reviews were very mixed and the game became an outright flop in the West. And although the sale numbers amongst the intended Japanese audience certainly was better, they ultimately fell short of Nintendo's expectations. But the icing on the cake is the fact that in many places it has even become an illustrative example of how NOT to write a story and female characters in a video game...
Troubled Production: The producer, the developer and the publisher all had different ideas for Other M that simply didn't mix. Yoshio Sakamoto was originally going to follow the series' Show, Don't Tell formula, but since Nintendo wanted to appeal to the Japanese fanbase, this meant tweaking the game's story into actually having a story, which Sakamoto decided would be a good opportunity to flesh out Samus' character as he envisioned her. Team Ninja, who is known for making gratuitous action games featuring Action Girl protagonists and only minor cutscenes to keep the plot cohesive, found themselves heavily railroaded with Other M being so exposition-heavy and Samus being feminized constantly, which wasn't helped by Sakamoto directing most of the storytelling. The end result was a mess of Plot Holes, Aborted Arcs and hugeValues Dissonance that was not only openly mocked by the Westerners that make up most of Metroid's fanbase, but ultimately failed to win over the Japanese audience, some of which hated Samus' "normal Japanese woman" characterization that was meant to win them over in the first place.