- "And I was right to believe that my boy and all his freaky buddies would see this thing through. But you know the only thing missing from that big show of yours? Music"
- —Hank Heywood
While on a mission to find Ray, Constantine and Nora discover Neron’s evil plan. Nate convinces the Legends to think outside the box and suggests a dangerous plan to unite magical creatures and people to save the world.
Preparation ran from December 20, 2018 until January 11, 2019, with a winter break from December 22, 2018 until January 4, 2019. Shooting ran from January 14 until January 24, 2019.
- The title references the name of the theme park that Hank wanted to create for Nate. It may also reference the Legends introducing themselves to the world in this episode.
- This episode marks the first appearance of Vandal Savage since "".
- After Ava and Zari comment that they should have reached out to the real Trinity (Supergirl, Green Arrow, and The Flash). Sara says that she did ask, but they said no. Nate responds that they (the Legends) "should have done the crossover", a meta-reference to the fact that the Legends were not in the crossover with Supergirl, Green Arrow, and Flash, despite confirmation in "" from Gideon and Ray that they were invited, but chose not to attend.
- Astra takes sixteen soul coins of history's greatest monsters, including Joseph Stalin, the leader of the Soviet Union, and Caligula, who in history is known as one of the worst Roman emperors of all time as well as Mary Tudor, Genghis Khan, Lizzie Borden, John Wayne Gacy, Charles Manson and Grigori Rasputin and eight others.
- When the Legends are discussing finishing Heyworld to teach the public that magical creatures are nothing to be afraid of, Sara says "If we build it..." Ava then finishes Sara's sentence by saying "They will come." This is a famous quote from the 1989 film Field of Dreams.
- Nora hitting Ray's chest is a parallel to similar scenes in "" and "".
- Behrad wears the same shirt under his jacket as worn by Zari in "".
- As of this episode, the only remaining Legends from the first three seasons are Sara, Ray, Mick, Gideon, and Nate.
- Rip Hunter, Leonard Snart, Carter Hall, and Martin Stein are all deceased.
- Kendra Saunders, Scythian Torvil, Jefferson Jackson, Amaya Jiwe, and Wally West have all retired from the Legends.
- Constantine, Nora, Ava, and Gary were in season 3, but none joined the Legends until this season.
- Zari's time as a Legend has been erased from the timeline, replacing her with Behrad. However, Tala Ashe has been confirmed to return next season.
- Constantine states that it will take more than a musical number to fix everything. This is a reference to "", as well as an ironic foreshadowing of the Legends singing to bring Nate back from the dead.
- Ironically, in episode "", Barry Allen mentioned that his mother once said that "musicals have the power to make everything better", which is what ends up happening in this situation.
- "Sweet Baby James", the song that Hank, the Legends and the people visiting Heyworld use to resurrect Nate, was also sung by Hank to soothe the Minotaur in "". Coincidentally, the same Minotaur plays accompaniment in this rendition.
- The way that they start singing the song, with Hank's spirit being channeled through Mick to get everyone to join in, is similar to "", in which Hank's spirit is also channeled through Mick, but for another reason.
- Phil Klemmer has revealed that the singing in this scene was recorded live on-set, and Dominic Purcell (who portrays Mick) sang his line without rehearsal.
- As of this episode, it's possible that Nate's identity as Steel is no longer a secret; he continues to not use his helmet, and Sara calls him by name while gathering Heyworld's guests to sing.
- When the Legends are trying to get Heyworld's visitors to join in the song, Gary says that they need everyone to hold hands. Nora then asks "Didn't they do this last year?" and Ava responds "We're part of the circle this time." This is a reference to the season 3 finale "", in which the Legends (specifically Nate, Sara, Wally, Mick, Zari and Amaya) form a circle and hold hands to combine the powers of the Totems of Zambesi to conjure something to destroy Mallus.
- Gideon mentions the Anti-Meta-human Act of 2029, but it was previously mentioned in "" that that law came into effect in 2021.
- However, it's possible that ripples due to time travel caused the law to come into effect later than it had in the previous timeline, or that two Acts of the same name, passed in different years, exist, as often occurs in the real world.
- After Nate's death, Sara is shown hugging Ava in the background from a front view, but she is suddenly next to Zari when the camera moves above them.
- Ray and Zari can be heard singing at various points in "Sweet Baby James", though neither of their mouths are moving except in Zari's solo at the beginning of the song.
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