- Awesome, Dear Boy: Pierce Brosnan summed up his reason for doing the film as this: "Meryl Streep is starring." Perfectly understandable. Many people would use the same reason...
- California Doubling: The scene where Sam, leaves his New York office to go to the Greek Island was actually filmed at the Lloyd's Building on Lime Street in the City of London. He dashes down the escalators and through the porte-cochere, where yellow cabs and actors representing New York mounted police were used for authenticity.
- The Cover Changes the Gender: ABBA's "Does Your Mother Know" was originally sung by the men in the group. In Mamma Mia!, it is sung by the character Tanya.
- Cut Song: The "Under Attack", "One of Us", "Knowing Me, Knowing You", and "The Name of the Game" numbers from the musical do not appear in movie (although "The Name of the Game" sequence is a Deleted Scene). All but the first one would go on to appear in the sequel.
- Early previews of the stage show featured "Summer Night City". It was cut when the show officially opened, although it is still used instrumentally as scene change music at one point in Act II. It is believed that it was cut due to nearly the entire cast (minus the dads) being introduced over the course of a single musical number.
- Dawson Casting: Donna is supposed to be in her early forties, but Streep was nearly sixty when she did the role. In fact, nearly all of the middle-aged adults are played by actors close to retirement age. Colin Firth was 48 at the time of filming, so he averts this trope by being of the right age.
- Non-Singing Voice: Averted, as no voice doubles were cast. This may have negatively affected the film's critical reception, particularly in the case of Pierce Brosnan.
- Playing Against Type: Meryl Streep. Yes, the same Streep who starred in Sophie's Choice. Then again, one could argue that she doesn't really have a type at this point.
- Promoted Fanboy: Meryl Streep was a fan of the stage show after seeing it on Broadway in September 2001, when she found the show to be an affirmation of life in the midst of the destruction of 9/11.
- Romance on the Set: Amanda Seyfried and Dominic Cooper dated for two years, but broke up due to him staying in the UK while she stayed in the United States.
- Star-Making Role:
- Throw It In!:
- Donna's famous straddle split jump during "Dancing Queen" came about because Meryl Streep decided she wanted to see if she could do it, and it was caught on tape. When she was asked to try it again, she said there was no way she'd ever be able to replicate it.
- Donna rips Sam's shirt off during the fountain scene because... Meryl felt like ripping Pierce Brosnan's shirt off. That's it. Brosnan's surprise (and enthusiasm) are absolutely real.
- Apparently, the eye tattoos on Bill's bottom were Stellan Skarsgård's idea, and he didn't tell the director. When they filmed the scene, she howled laughing.
- What Could Have Been:
- Michelle Pfeiffer and Olivia Newton-John were considered for Donna.
- Bill Nighy was considered for one of the dads.
- Cher turned down the role of Tanya due to concert commitments. She went on to appear in the sequel.
- Amanda Bynes, Rachel McAdams, Mandy Moore and Emmy Rossum were for Sophie.
- Dawn French was originally cast as Rosie. After the creators described her character as "the fat, funny one," and the musical director was clearly not impressed with her singing, she declined the role.
Trivia / Mamma Mia!