Mass Effect
Mass Effect - Did You Know Gaming? Feat. Really Freakin Clever
According to Drew Karpyshyn, a writer for the Mass Effect series, Dr. Chakwas's name is an anagram of the word "hacksaw". This was chosen to "evoke an old timey saw-bones field surgeon,".
Contributed by Psychospacecow
To create an establishing visual look for the game's world that could compete with the likes of Star Wars' visual style, long smooth circular arcs were incorporated into all of the characters, aliens, ships, armor and weapons, and even the logo. The style was inspired by some of the artists working on the game, especially from the artwork by one of the game's artists, Syd Mead.

Because the previous generation of games couldn't achieve smooth polygons, this style was instrumental in convincing the public that Mass Effect was a real next-gen game.
Contributed by KnowledgeBase
The iconic Reaper roar from the Mass Effect series is the sound of a bear-proof trash can opening and closing. When the sound was played for Casey Hudson, the series' project director, he immediately said "that's the sound of the Reapers."
Contributed by t4br1s
The artist who designed the Krogan race used bats and insects as references.
Contributed by Psychospacecow
Mass Effect's protagonist Commander Shepard is named after Alan Shepard, the first American in space and the fifth person to walk on the moon. Shepard's birthday (April 11) is also a reference to the Apollo 13 space mission (launched on 11 April 1970.), which Shepard was originally assigned to before commanding the Apollo 14 mission.
Not long after Mass Effect 2 was released, BioWare started developing a spin-off downloadable Mass Effect game which never saw the light of day. It would have been called 'Mass Effect: Team Assault' and would appear to have been a first-person shooter with a large multiplayer aspect to it. Although scrapped just 4 months into development, early prototype footage exists and the basis later evolved into the multiplayer of Mass Effect 3.