The soundtrack album featured a cover of "The Day Before You Came" sung by Meryl Streep. The track was only recorded because it was one of Benny Andersson's and Richard Curtis' favorites ABBA songs and Streep wanted to sing it, but it was never actually in this movie as the lyrics are too specific to have fit in with the story.
Producers have discussed the idea of making a third film. Amanda Seyfried said she would be on board for another movie, but has questioned if there are enough unused ABBA songs for a third soundtrack. Julie Walters, who has retired from acting, has said that a third Mamma Mia film would be her one and only reason for coming out of retirement.
Cher handpicked Andy Garcia to play the character of Fernando out of a bunch of selected actors.
Dame Julie Walters was given a day off from the Shepperton Studios filming in November 2017 (during the taping of the "Angel Eyes" number) so she could attend an investiture ceremony at Buckingham Palace, where she was made a Dame Commander of the Order of the British Empire by Queen Elizabeth II. The cast and crew garnered to surprise and welcome Walters back while singing "There Is Nothing Like a Dame" from the musical South Pacific.
Had the biggest opening weekend at the box-office in the careers of Meryl Streep, Amanda Seyfried, and Cher.
Björn Ulvaeus: The ABBA member makes a cameo appearance in the number "When I Kissed the Teacher" as a college chancellor.
Benny Andersson: Appears as a piano player during the Waterloo number. He also appears briefly in the "When I Kissed the Teacher" scene. Andersson is one of the members of ABBA, on whose songs the musical was based.