- "I have spent so much time with you guys. You're my family now. You deserve to be happy and if I can be a small part of making that happen then this will be worth it."
- —Zari Tomaz
After the team returns from a mission, Zari finds herself trapped in a time loop that results in the Waverider blowing up over and over again. Zari soon begins to suspect that the answer to stop what is happening might lie hidden among her fellow shipmates’ secrets. But in investigating them she starts to understand her place on the team.
- This episode's title is a reference to the eponymous line "Mamma mia, here I go again" from the ABBA song "Mamma Mia", which is spoken by Zari Tomaz before the second Waverider explosion during the time loop.
- To the shock of Z and the audience, Mick is attempting to write a novel.
- Nate has Zari reference the 1993 film Groundhog Day in order to explain her time loop predicament to him.
- Ray references the Star Trek: The Next Generation episode "Cause and Effect", in which the characters experience a similar time loop, leading to the repeated destruction of the USS Enterprise.
- This episode features Vivaldi's 'Concerto No. 4 in F minor, Op. 8, RV 297, "Winter": Largo. Zari is shown playing the song, referencing actress Tala Ashe's real-life experience in playing the violin.
- Amy Pemberton makes an appearance as Gideon in human form. This is the second time she has appeared in person after the second season episode "Land of the Lost", although she makes a pseudo-appearance in a photograph in the third season premiere "Aruba-Con".
- Hawkgirl's helmet is seen in Zari's “fun montage” scene, though Zari adopts a Catwoman-esque pose while wearing it.
|DC's Legends of Tomorrow season 3|
|"Aruba-Con" • "Freakshow" • "Zari" • "Phone Home" • "Return of the Mack" • "Helen Hunt" • "Welcome to the Jungle" • "Crisis on Earth-X, Part 4" • "Beebo the God of War" • "Daddy Darhkest" • "Here I Go Again" • "The Curse of the Earth Totem" • "No Country for Old Dads" • "Amazing Grace" • "Necromancing the Stone"|
|"I, Ava" • "Guest Starring John Noble" • "The Good, The Bad and The Cuddly"|