[3] Her father, Niels, was born in Ledbury, Herefordshire, but lived with his Danish parents in the parish of Raklev [nl], near Kalundborg on the island of Zealand, until the age of four.

[15] On 16 October 2014, she scored the only goal to help Manchester City defeat Arsenal Ladies and win the 2014 FA WSL Continental Cup.

[17] In her first season with the club, Lyon won the treble: winning Division 1 Féminine, Coupe de France and Champions League.

[25] Coach Mark Sampson gave Christiansen her senior international debut in a UEFA Women's Euro 2017 qualifying match against Estonia on 21 September 2015.

[26][27] In March 2019, Christiansen underwent surgery on an ankle injury sustained in England's 3–0 SheBelieves Cup win over Japan.

[28] England coach Phil Neville called her "vital" to his squad and hoped that her rehabilitation programme would restore her to fitness for the 2019 FIFA Women's World Cup.

[29] Christiansen was allotted 189 when the FA announced their legacy numbers scheme to honour the 50th anniversary of England’s inaugural international.

[33] By joining the charity, players pledge at least one percent of their salaries to a community fund that supports young people's football in around 90 countries.