Crisis on Earth-X, Part 3 - S4-E8
Trivia: Supergirl says to her doppelganger "General, can you step outside." That line was said by Superman in Superman II.
Going Rogue - S1-E4
Trivia: Kahndaq is mentioned heavily in this episode. Kahndaq is a fictional country, home to DC anti-hero, Black Adam.
Attack on Gorilla City - S3-E13
Trivia: Julian asks Barry "are you gonna go to the planet of the apes?" Tom Felton played Dodge Landon in the modern remake of that film.
Trivia: Robbie Amell, who plays Caitlin's fiancee Ronnie, is the cousin of Stephen Amell, who plays the lead role on Arrow.
Trivia: In the auto shop Dr Stein walks in with Barry Allen. Dr Stein insults the music playing. Jefferson Jackson says to him "I got the Titanic soundtrack in the back there." Dr Stein played the captain in the Titanic movie. (00:10:15)
Trivia: Tom Cavanagh, who plays Reverse-Flash after he assumes Dr. Wells' identity, and Matt Letscher, who plays Reverse-Flash/Eobard Thawne, played father and son on Eli Stone.
Trivia: When The Atom first appears, the characters say "It's a bird" "It's a plane", an obvious reference to Superman, played by Brandon Routh in "Superman Returns", who also plays The Atom in this episode.
Tricksters - S1-E17
Trivia: Mark Hamill plays James Jesse, the original Trickster, a role he also played twenty-five years earlier in the 1990 Flash TV series.
Things You Can't Outrun - S1-E3
Trivia: The movie Barry and Iris are leaving is entitled Blue Devil II. A reference to DC Comics superhero Blue Devil, who was a stuntman that worked on the in-universe "Blue Devil" films.
Trivia: Starting in season 4, Jessica Parker Kennedy plays Nora West-Allen, also known as "XS." In the TV series "Smallville", Kennedy plays Plastique. In the comics, Plastique's first appearance was in "The Fury of Firestorm" #7. Firestorm was a reoccurring character in "The Flash", mainly in season 1.
Trivia: Cisco plays the Queen song "Flash" while Barry is running through the black hole. This song is actually a reference to Flash Gordon (used as the theme song for the 1980 film), not the speedster named Flash.
Trivia: There is a reference to Smallville TV show in the opening scene among the heroes - Green Arrow played by Justin Hartley is lying on the ground.
Trivia: The music made by Danny Elfman for Batman and The Flash movies can be heard in Gotham city.
