
"Brick Like Me" is the twentieth episode of the twenty-fifth season of the American animated television series The Simpsons and the 550th episode of the series. It first aired on the Fox network in the United States on May 4, 2014. It was written by Brian Kelley and directed by Matthew Nastuk. The episode features a mix of traditional animation and computer animation. In the episode, Homer wakes up in an alternate reality where everyone and everything is made of Lego bricks, and he must figure his way out before he gets stuck in the plastic world forever. This episode won the Writers Guild of America Award for Outstanding Writing in Animation at the 67th Writers Guild of America Awards.

"But Can She Type?" is the second segment of the thirteenth episode from the first season (1985–86) of the television series The Twilight Zone. In this segment, a secretary travels to an alternate dimension where secretaries are revered in a manner similar to A-list movie stars and fashion models in the real world.

"Crisis on Earth-X" is the fourth annual Arrowverse crossover event, featuring episodes of the live-action television series Supergirl, Arrow, The Flash, and Legends of Tomorrow on The CW. The crossover began on November 27, 2017, with Supergirl and Arrow, and concluded on November 28, with The Flash and Legends of Tomorrow. In "Crisis on Earth-X", Barry Allen and Iris West's friends come to Central City for their wedding, only for the proceedings to be interrupted by interlopers from the analogous universe of Earth-X, where the Axis powers claimed victory in World War II.

"Crisis on Infinite Earths" is the sixth annual Arrowverse crossover event and features episodes of the television series Supergirl, Batwoman, The Flash, Arrow, and Legends of Tomorrow on The CW. The Supergirl, Batwoman, and The Flash episodes aired in December 2019 while the Arrow and Legends of Tomorrow episodes aired in January 2020. The events of the Black Lightning episode "The Book of Resistance: Chapter Four: Earth Crisis" and a two-issue comic book with characters and concepts unused in the live-action episodes also tied into the event.

"The Daedalus Variations" is the 84th episode of the science fiction television series Stargate Atlantis, and is the fourth episode in the series' fifth season. The episode first aired on August 1, 2008 on the Sci Fi Channel in the United States, and subsequently aired on October 9 on Sky One in the United Kingdom. The episode was written by Alan McCullough, and directed by regular Stargate director, Andy Mikita. Richard Woolsey and Jennifer Keller do not appear in the episode, despite being credited during the opening title sequence. Talking to journalists, McCullough linked the story to that of the Flying Dutchman, a mythical ghost ship that drifts forever in the ocean with no chance of returning home. The episode received generally favourable reviews.

The Day After Tomorrow is a 1975 British science-fiction television special produced by Gerry Anderson between the two series of Space: 1999. Written by Johnny Byrne and directed by Charles Crichton, it stars Brian Blessed, Joanna Dunham, Nick Tate, Katharine Levy and Martin Lev, with narration by Ed Bishop. Set in a future where environmental damage on Earth threatens the survival of humanity, The Day After Tomorrow follows the interstellar mission of Altares, a science vessel that uses photon energy to travel at the speed of light. After leaving the Solar System and reaching Alpha Centauri, their primary destination, the crew of Altares push deeper into space; there, they encounter phenomena including a meteor shower, a red giant and, finally, a black hole, which pulls the ship into another universe.

"Dimension Jump" is the fifth episode of science fiction sit-com Red Dwarf Series IV and the twenty-third episode in the series run. It was first broadcast on the British television channel BBC2 on 14 March 1991, written by Rob Grant and Doug Naylor, and directed by Ed Bye. The episode, featuring the first appearance of Ace Rimmer, was intended to end the series; but Meltdown was rescheduled and broadcast last due to the Gulf War.

"Doomsday" is the thirteenth and final episode in the second series of the revival of the British science fiction television programme Doctor Who. It was first broadcast on 8 July 2006 and is the conclusion of a two-part story; the first part, "Army of Ghosts", was broadcast on 1 July 2006. The two-part story features the Daleks, presumed extinct after the events of the 2005 series' finale, and the Cybermen, who appeared in a parallel universe in the 2006 episodes "Rise of the Cybermen" and "The Age of Steel". Both species unexpectedly arrive on Earth at the conclusion of "Army of Ghosts".

Dual! Parallel Trouble Adventure is a Japanese anime series animated by AIC and created by Masaki Kajishima, best known for the Tenchi Muyo! franchise. It was originally broadcast on Wowow from April to July 1999 and was licensed in the US by Pioneer LDC, later known as Geneon. In addition to the original TV run, an OVA special was added to conclude the series as a de facto "14th episode".

"Duet" is the seventeenth episode of the third season of The CW television series The Flash, which aired on March 21, 2017. The episode was written by Aaron Helbing and Todd Helbing from a story by Greg Berlanti and Andrew Kreisberg, and was directed by Dermott Daniel Downs. The episode features a musical crossover with Supergirl and reunites Grant Gustin and Melissa Benoist with their former Glee co-star Darren Criss, who portrays the Music Meister. Jesse L. Martin also reunites with Jeremy Jordan, with whom he previously worked in the 2012 musical film Joyful Noise. The story begins at the end of the Supergirl episode "Star-Crossed", which aired on March 20, 2017, which saw Kara Danvers / Supergirl (Benoist) hypnotized into a coma by Music Meister, with Mon-El and J'onn J'onzz / Martian Manhunter bringing her to Earth-1 in hope that Team Flash can save her.

"Elseworlds" is the fifth annual Arrowverse crossover event that features episodes of the live-action television series The Flash, Arrow, and Supergirl on The CW. The crossover event began on December 9, 2018, with The Flash, continued on Arrow on December 10, and concluded on Supergirl on December 11. "Elseworlds" introduces the characters Batwoman and Lois Lane, and the fictional Gotham City, to the universe. In the crossover, Green Arrow, Flash, and Supergirl are drawn to Gotham City to confront Dr. John Deegan over his work at Arkham Asylum.

"Gorilla City" is a two-part story arc across the thirteenth and fourteenth episodes of the third season of the American television series The Flash, based on the DC Comics character Barry Allen / Flash. A costumed superhero crime-fighter with the power to move at superhuman speeds, Barry is a crime-scene investigator who gains superhuman speed which he uses to fight criminals, including others who also have superhuman abilities. The series is set in the Arrowverse, sharing continuity with the other television series of the universe, and is a spin-off of Arrow. The storyline began on February 21, 2017 with "Attack on Gorilla City", and concluded on February 28 with "Attack on Central City". The first episode was written by Aaron Helbing and David Kob from a story by Andrew Kreisberg, and the second episode was written by Benjamin Raab and Deric A. Hughes from a story by Todd Helbing. Both episodes were directed by Dermott Daniel Downs.

"Invasion!" is the third annual Arrowverse crossover event, with episodes of the television series The Flash, Arrow and Legends of Tomorrow on The CW, and is inspired by the 1989 comic miniseries Invasion!. Events at the end of the Supergirl episode "Medusa" on November 28, 2016, marked the beginning of the crossover, which began on November 29 with The Flash, continued on Arrow on November 30, and concluded on Legends of Tomorrow on December 1. Each of the main three episodes were titled "Invasion!". In the crossover, Barry Allen recruits Kara Danvers / Supergirl from Earth-38 to Earth-1 to help his team, Oliver Queen and his team, and the Legends to defeat the alien race known as the Dominators.
"Mirror Image" is episode 21 of the American television anthology series The Twilight Zone. It originally aired on February 26, 1960 on CBS.

"Parallel Universe" is the sixth episode of science fiction sitcom Red Dwarf series two, and the twelfth in the show's run. It premiered on the British television channel BBC2 on 11 October 1988. Written by Rob Grant and Doug Naylor, and directed by Ed Bye, the plot involves the Red Dwarf crew travelling to a parallel universe where they meet alternative versions of themselves. This marked the final appearance of Norman Lovett as Holly, although he would return years later at the end of Series VII and then for the whole of Series VIII. The episode was re-mastered, along with the rest of the first three series, in 1998.

"Road to the Multiverse" is the first episode of the eighth season of the animated comedy series Family Guy. Directed by Greg Colton and written by Wellesley Wild, the episode originally aired on Fox in the United States on September 27, 2009, along with the series premiere of The Cleveland Show. In "Road to the Multiverse", two of the show's main characters, baby genius Stewie and anthropomorphic dog Brian, both voiced by series creator Seth MacFarlane, use an "out-of-this-world" remote control to travel through a series of various parallel universes. They eventually end up in a world where dogs rule and humans obey. Brian becomes reluctant to return to his own universe, and he ultimately ends up breaking the remote, much to the dismay of Stewie, who soon seeks a replacement. The "Road to" episodes which have aired throughout various seasons of Family Guy were inspired by the Road to ... comedy films starring Bing Crosby, Bob Hope and Dorothy Lamour, though this episode was not originally conceived as a "Road to" show.

"Spookyfish" is the fifteenth episode of the second season of the American animated television series South Park. The 28th episode of the series overall, it originally aired on Comedy Central in the United States on October 28, 1998. The episode was written and directed by series co-creator Trey Parker. It was the season's Halloween special, featuring the "spooky" theme of having pictures of Barbra Streisand in the screen corners, accompanied with the words "Spooky Vision".

"Treehouse of Horror XXVIII" is the fourth episode of the twenty-ninth season of the American animated television series The Simpsons, the 28th episode in the Treehouse of Horror series of Halloween specials, and the 622nd episode of the series overall. It aired in the United States on Fox on October 22, 2017.

"Treehouse of Horror XXXI" is the fourth episode of the thirty-second season of the American animated television series The Simpsons, and the 688th episode overall as well as the thirty-first "Treehouse of Horror" episode. It aired in the United States on Fox on November 1, 2020. The episode was directed by Steven Dean Moore, and written by Julia Prescott.

"Turn Left" is the eleventh episode of the fourth series of British science fiction television series Doctor Who. It was written by showrunner Russell T Davies and broadcast on BBC One on 21 June 2008.

"Twentica" is the first episode of science fiction sitcom Red Dwarf series XI, originally broadcast on the British television channel Dave on 22 September 2016, and made available early on 15 September on UKTV Play. The show again continued in its "classic" format of six standalone half-hour episodes, initially returned to in Series X four years previously.
"A World of Difference" is episode 23 of the American television anthology series The Twilight Zone.

"Worlds Finest" is the eighteenth episode in the first season of the CBS television series Supergirl, which aired on March 28, 2016. The episode's teleplay was written by Andrew Kreisberg and Michael Grassi, and directed by Nick Gomez.