For years, Mass EffectFan Fiction writers have used the idea of the male and female versions of Shepard being brother and sister as an excuse to include both in the story. For Andromeda, the developers themselves decided to use that idea so they could include both versions of Ryder.
Also in the case of Jaal, many fans expected him to be bisexual in the game and went as far as spread rumors about their perceived sexual orientation of the character, with support from the findings of dataminers. When the game actually came out, Jaal was indeed revealed to be a romance option but only for a female Ryder. The developers after listening to some feedback from fans, eventually decided to officially make Jaal bisexual and made him a romance option for a male Ryder when the game was updated by patch 1.08.
Creator Killer: In May 2017 it was revealed that Bioware Montreal had been turned into a support studio, with part of their staff moved over to EA Motive. Then in July 2017 EA announced Bioware Montreal would be shut down and fully absorbed by EA Motive, while developers on Twitter confirmed that the Mass Effect IP was back in the hands of Edmonton.
According to several Bioware artists who worked on the game and spoke to YouTuber Liam Robertson, upper management decided facial models and animations of human characters were to be completely outsourced to another EA studio, possibly EA Bucharest, because they did not see them as important enough to be done by the studio employees themselves. Bioware artists were not even allowed to polish the faces and animations done by the other studio in any way.
After the reveal that male and female Ryder are siblings and the N7 explorer is their father, the usage of the terms "Bro!Ryder", "Sis!Ryder", and "Ry!Dad", respectively, have become used in the fanbase.
Before (and to a lesser extent still after) her name was revealed, Peebee was referred to by fans as the "Raccoon" or "Hamburglar Asari" thanks to her distinctive dark streak across her eyes. Others call her Blue Shrek because of some similarities in the faces.
Doctor Lexi, the asari med bay officer, is modeled and voiced after actress Natalie Dorner, leading many of her fans to label her "Doctor Sexi".
The name of the new protagonist, Ryder, was essentially old news to the fanbase by the time it was confirmed at E3 2016, which had correctly guessed it from the dog tag found in the N7 Day teaser (which, incidentally, does notbelong to the protagonist, but likely their father Alec Ryder).
A lot of people correctly guessed that Liam was going to be a love interest despite no information regarding him as such.
Meaningful Release Date: Unintentionally. The game is being released in North America on March 21, 2017, which reads as "3/21" on American calendars. BioWare Director Aaryn Flynn has said the developers didn't even realize the significance of the release date until fans pointed it out to them.note The significance being that the date is jokingly referred to as "3, 2, 1... (launch!)", which fits the game's space theme.
Kumail Nanjiani, the voice of Jarun Tann, has said that playing the first three games was his favorite gaming experience.
The entire idea behind the "Explorers Wanted" contest, in which fans got to submit auditions to Bioware with the winners being selected to voice minor characters in the game. Cari Sholtens and Kyle Land won respectively.
The two voice actors for the Ryder siblings (Tom Taylorson and Fryda Wolff) previously played two other characters with a familial relationship in a video game: Octodad and his daughter Stacy. Subtly referenced in this promo video where Fryda looks at Tom in the recording booth and makes "blub blub blub" sounds. It's the only sound Octodad ever makes.
Word of Gay: The update patch 1.08 revealed that Jaal is bisexual even though he was originally only available for a female Ryder. The use of this trope on Jaal was suggested by fans and eventually made canon by the game developers.