[1] In one of the most unexpected results at these Games, Canadian teenager Penny Oleksiak and U.S. sprinter Simone Manuel pulled off an enormous upset from Australia's pre-race favorites Bronte and Cate Campbell down the home stretch to be in a dead heat for the gold medal.

[2] About midway of the final lap, both Oleksiak and Manuel came from behind to overhaul almost the entire field, before touching the wall simultaneously for an Olympic record in 52.70.

[7] Sweden's Sarah Sjöström captured the bronze with a 52.99 to complete a full set of medals at the Games, edging out Bronte Campbell (53.04) to fourth by a 0.05-second deficit.

[8][9] Dutch sprinter Ranomi Kromowidjojo missed her chance to defend the title with a fifth-place time in 53.08, while world-record holder Cate Campbell, who broke the existing Olympic record in the heats and then again in the semifinals, slipped to sixth in 53.24.

[9] Notable swimmers missed the final roster, including Brazil's home-crowd favorite Etiene Medeiros, Belarus' two-time Olympic medalist Aliaksandra Herasimenia, and Italy's Federica Pellegrini, who scratched the afternoon prelims earlier to focus on her 4 × 200 m freestyle relay duty instead.