- Cash Cow Franchise: This should come as no surprise considering what both Mario and Sonic are on their own, even more so considering that they're competing in the biggest sporting event in the world.
- Delayed Release Tie-In: Tokyo 2020 is obviously a tie-in to the Tokyo Olympics, which would be postponed until 2021 due to the 2020 coronavirus pandemic.
- Dummied Out: Donkey Kong, Silver, Birdo, a Goomba, and an Egg Pawn were originally going to be playable in Beijing 2008, but were cut due to time constraints. Donkey Kong, Silver, and Birdo would be playable in later installments.
- Fandom Nod: Introduced in Mario & Sonic at the Sochi 2014 Olympic Winter Games, an event, Figure Skating Pairs, allows the player to select a male and female character to be paired with each other.
- The Other Darrin:
- In the original installment, Peach was voiced by her former voice actress Jen Taylor, but has been voiced by her current voice actress Samantha Kelly from Vancouver 2010 onwards.
- London 2012 onwards utilizes the Studiopolis Sonic voice cast introduced in 2010's Sonic Colors (with returning voice actor Mike Pollock recording new lines for Dr. Eggman). Furthermore, this is also the first Mario and Sonic game where Kenny James replaces Scott Burns's archived recordings as the voice of Bowser (although he did voice Dry Bowser in Vancouver 2010).
- The first two installments are also the primary place to hear Vector voiced by Dan Green, replacing Jimmy Zoppi after he stopped working for 4Kids.
- Rio 2016 is the first game in which Matthew Mercer takes over the role of Espio from Troy Baker, which considering the actors involved was probably fine.
- Due to Chikao Ohtsuka's death from ischemic heart failure in January 2015, Kotaro Nakamura replaced him as Eggman for Rio 2016, effectively making him the de facto voice of the character. Interestingly, Ohtsuka's voice clips were still retained for Eggman Nega.
- Tokyo 2020 carries over four voice actor changes from Team Sonic Racing: Dave B. Mitchell replacing Travis Willingham as Knuckles, Erica Lindbeck replacing Laura Bailey as Blaze, Bryce Papenbrook replacing Quinton Flynn as Silver, and Patrick Seitz also replacing Willingham as Zavok.
- What Could Have Been:
- Silver the Hedgehog and Donkey Kong, who are playable characters in the second game onwards, were planned to appear in the first one in the same capacity. Birdo and Jet the Hawk were to appear in the first game as playable characters too, but they ended up in the second game as a VIP audience member and a Festival Mode rival character, respectively.
- The Olympic Games games also caused a What Could Have Been on an unrelated Sonic game: Sumo Digital thought up of the possibility of having Mario as a guest character for the Wii version of Sonic & Sega All-Stars Racing (for reasons that should be obvious) but didn't go ahead because of the mere existence of these games, feeling that Sega would be cash-cowing both Mario and Sonic too much otherwise. (This also had the side effect of letting Microsoft go unopposed with their own guest racers for the Xbox 360 version, not to mention the fact that Sonic has been playable in the Super Smash Bros. series alongside Mario since Brawl, which was released about 2 years before All-Stars Racing).
- Swimsuits for Peach and Daisy were planned for the first game, but were scrapped by Nintendo. They eventually got their swimsuits in the London 2012 game, although swimsuits were also planned for all characters, but the idea was rejected by Sega since it would be mean having Sonic's shoes removed.
- Zeena was originally gonna appear as a playable character in Tokyo 2020, as evidenced in unused announcer voice clips.
Trivia / Mario & Sonic at the Olympic Games