Had the biggest opening weekend at the box office in the careers of Meryl Streep, Amanda Seyfried and Cher.

Meryl Streep and Lily James, the two actresses portraying Donna, are distant relatives - ninth cousins, three times removed to be precise.

Released a decade to the month after its predecessor Mamma Mia! (2008).

Cher handpicked Andy Garcia to play the character of Fernando out of a bunch of selected actors.

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 South Pacific musical.

Amanda Seyfried was told by her agent that the film had been officially green-light, exactly on the day she came home from the hospital, after giving birth to her daughter.

When young Donna and the group leave the graduation, they end up on the dock where a small boat is shown with the name Chiquitita (an ABBA song used in the 1st film).

Cher is just three years older than Meryl Streep, despite them playing mother and daughter.

After appearing in this film, Cher decided to make a full album of ABBA covers, aptly titled "Dancing Queen".

The musical score played during the film is a mostly comprised of songs featured in the first film and unused ABBA songs.

Despite being an actress for over 40 years, this film marks the first time in her career that Meryl Streep has ever done a sequel.

The first time Julie Walters met Cher, she ran up to her in a rush of excitement and gave her a warm hug. However, Walters' glasses got stuck in Cher's white wig, leaving it tarnished, and a new wig had to be used for filming.

Lily James had a broken toe while filming the "Waterloo" number

Cher was originally offered the role of Tanya in the first film which she turned down. She appears in this movie but in a different role, per invitation of her former agent and dear friend, Ron Meyer, who is now head of Universal Studios.

The trailer sets Donna (Meryl Streep)'s pregnancy in 1979, and the birth of Sophie as 1980, which sets Mamma Mia! (2008) around 2000, as Sophie is 20. The movie is set 5 years after the first film, which would make this 2005.

The film choreographer is the same choreographer who worked with the traveling Mamma Mia North American Farewell Tour.

Stellan Skarsgård, Jeremy Irvine and Colin Firth also co-starred together in The Railway Man (2013), where Irvine played the younger version of Firth's character. In Mamma Mia! Here We Go Again, Irvine plays the younger version of Pierce Brosnan's character.

Hugh Skinner (Young Harry) and Amanda Seyfried (Sophie) both appeared in the 2012 film Les Misérables (2012) with Skinner playing Joly and Seyfried playing Cosette.

Lily James and Stellan Skarsgård also appeared in the live action version of Disney's Cinderella. James played Cinderella and Skarsgård played the Grand Duke.

Cher, who is playing Sophie (Amanda Seyfried)'s grandmother in this movie, had a cameo in ABBA's last video in 2004, named ABBA: Our Last Video Ever (2004). The video was released due to ABBA's 30th anniversary since the winning of the Eurovision Song Contest 1974 (1974). In the video, Cher was an audience member while ABBA, portrayed by puppets, performer their winning song "Waterloo."

This film marks the second film collaboration between Cher and Meryl Streep, the first being Silkwood (1983). They were also in Stuck on You (2003) together where Meryl Streep made an uncredited appearance in the movie.

When young Donna (Lily James) walks with young Harry (Hugh Skinner) in Paris by the fountain, he is wearing a Johnny Rotten t-shirt. This is referenced by Colin Firth in the first film before he sings 'Our Last Summer' when he refers to buying his guitar for "ten quid plus this Johnny Rotten t-shirt".

In the first film "Mamma Mia!" Donna (Meryl Streep) has blue eyes. Whilst in this film "Mamma Mia! Here we go again" Donna (Lily James) has brown eyes.

Harry Bright's (Colin Firth/Hugh Skinner) birthday is November 3, 1955.

There's a reference to the Beatles early on in the movie when Sophie is addressing the invitations for the party she is planning. One of the addresses is c/o Epstein Martin, a composite of the surnames of the Beatles manager Brian Epstein and their record producer George Martin.

Celia Imrie and Julia Walters previously appeared together in Dinnerladies (1998) and Calendar Girls (2003)

Josh Dylan (Young Bill) and Jeremy Irvine (Young Sam) had to wear hair pieces for their roles as they had short hair cuts at the time of filming. Christine Baranski also wore a brown wig while filming the movie.

The young cast did extensive research on their "legacy" counterparts by studying the first film and watching countless interviews and other film footage from their early days. Lily James was a fan of the musical from an early age and stated she had seen it over 10 times on stage.

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. Anderson is one of the members of ABBA which songs the musical is based on.

Meryl Streep (Donna) filmed all her scenes in one week.

The reveal of Bill Anderson's twin is a reference to the line in the first film, when he just realized he might be Sophie's father: "You're not going to tell me that you have a twin sister, are you?"

If you back track the timeline, Donna graduated college in 1978-79, she would have been 22-23 as degrees are 4 years in the UK. Thus she would have been born around 1956-1957. Fernando refers to being left by a woman, who later turns out to be Ruby, in 1955. It stands to reason that Fernando might be Donna's father and Sophie's grandfather.

The film's soundtrack album features a cover of "The Day Before You Came" by Meryl Streep, that is omitted from the final film. The track was the last one recorded by ABBA and their song with the second-longest running time.

The scenes shot for the musical number "I Wonder (Departure)" sung by Lily James, Jessica Keenan Wynn and Alexa Davies, were cut from the film, likely due to time constraints/pacing. The song is still featured in the film's soundtrack album though.

Although "Fernando" is one of ABBA's biggest hits - and also one of the top-selling singles in music history - the writers for both of the "Mamma Mia!" movies couldn't figure out a way to integrate a song centered around a (fictional) Mexican revolution of a past era into a musical set in modern-day Greece. At the last minute, however - after the sequel's script was nearly completed - they came up with the idea for Fernando to be both the hotel's love-lorn manager, as well as Ruby's long-lost love. This gave Cher an appropriately grand finale number for her character Ruby, along with the opportunity to sing one of the only major ABBA hits not previously used in the original musical or film (or up to the end of the sequel).

As in this movie as Sophie, Amanda Seyfried plays a young woman (Cosette), who loses her mother in Les Miserables and in both movies her mother appears in the final scenes as a ghost watching over her. The mother characters in both movies, Fantine and Donna, also sing songs on a theme of "I have/had a dream"

Despite Cher's singing career, this is only the second musical that she has appeared in (she was previously in "Burlesque".) It marks Meryl Streep's fourth musical (after the original "Mamma Mia!," "Ricki and the Flash", and "Into the Woods".)

While Cher is somewhat implausibly cast as the mother (Ruby) to Meryl Streep's character (Donna), despite Cher only being three years older than Streep in real life, Ruby's age had to be set at a point to frame the movie's final reveal: her 1959 Mexican romance with Fernando (Andy Garcia), the lugubrious hotel manager who never recovered from it. Given that Garcia was three years old in 1959, his casting is even more implausible, but Cher was purportedly allowed to choose the actor for the role, and her first choice was Garcia.