History Trivia / HowToTrainYourDragonTheHiddenWorld

* WhatCouldHaveBeen:
** When the film was first in production, WordOfGod revealed that Drago Bludvist would return from the second film and become a more developed character, possibly even performing a HeelFaceTurn. However, [=DeBlois=] later revealed after the release of the first trailer that Drago's intended role was removed in the script's rewrites.
** In the original draft, there was no Light Fury, and the hostage used to manipulate Toothless was ''Hiccup.'' Rather than order the dragons to submit, Toothless would take the opportunity to spring a trap-within-a-trap against Drago. This draft also contained a flock of other Night Furies.
** One of the storyboards drafted after the introduction of the Light Fury, but before the final cut, would have featured her being found in a cage aboard the trappers' ship and released straight off. In this scene, Toothless gently burns the harness muzzling her, and as his breath causes her scales to heat up, he literally sees himself in her.

* CastingGag: The warlord Ragnar is voiced by Icelandic actor Ólafur Darri Ólafsson, who had previously voiced Stoick the Vast in the Icelandic dubs of the previous two films. Ragnar shares a body model with Stoick.

* AdvertisedExtra: Eret son of Eret received this treatment. Despite Creator/KitHarington received his own promo video full of ActorAllusion, Eret's role is very minor and his biggest contribution to the plot is identifying the new BigBad Grimmel.

** Another storyboarded scene had Hiccup attempt to make Toothless and the Light Fury a "love nest" in New Berk to convince Toothless to bring her back there, before Valka arrives and discusses with Hiccup what really is best for their dragons.

** Many artists and fanfiction writers had already depicted a potential love interest for Toothless as pale/albino years ago.

* WhatCouldHaveBeen: When the film was first in production, WordOfGod revealed that Drago Bludvist would return from the second film and become a more developed character, possibly even performing a HeelFaceTurn. However, [=DeBlois=] later revealed after the release of the first trailer that Drago's intended role was removed in the script's rewrites.

* WordOfSaintPaul: According to Cressida Cowell, [[spoiler: Hiccup and Astrid's children are called Zephyr (girl) and Nuffink (boy)]], though this isn't mentioned in the film itself.

* FanNickname: The white female Night Fury-like dragon was given the nickname "Light Fury" by fans, although it soon turned out that this was what her species is actually called. Some have also taken to calling her "Nubless," and less charitably, "Girl Toothless."

* TheOtherDarrin: When the cast was announced, Creator/TJMiller was meant to reprise his role as Tuffnut in the film. Justin Rupple replaced him on account of Miller's [[RoleEndingMisdemeanor controversial behaviour in 2018]]. Also counts as TheOtherMarty in the context of this film.

** There was going to be a flashback of young Hiccup finding a wounded bird in the forest. Stoic would ask him to look away so he could end its pain, but Hiccup would plead to let him help the bird instead. Stoic would concede, but tell Hiccup it would be his responsibility to care for and heal the bird until he could release it into the wild again. The scene would thus have served as [[spoiler:foreshadowing for the ending with Hiccup letting Toothless go]].

** Deblois revealed in a behind-the-scenes video that [[spoiler: Hiccup and Astrid are both 30 years old in the epilogue, with nine years having passed between the dragons left]].

* WordOfGod: Director Dean [=DeBlois=] notes that the Light Fury is not another Night Fury, but a distinct relative of the species. Her ability to disappear through fireballs is caused by the fire heating her scales to become reflective of her surroundings.

* TheOtherDarrin: When the cast was announced, Creator/TJMiller was meant to reprise his role as Tuffnut in the film. Justin Rupple replaces him on account of Miller's [[RoleEndingMisdemeanor controversial behaviour in 2018]]. Also counts as TheOtherMarty in the context of this film.

* ReferencedBy: Mathew Buck reviewed it on ''WebVideo/{{Projector}}'' [[https://www.youtube.com/watch?v=rYt-3iR-ciY here]].

* AscendedFanon: "Light Fury" has been used before (albeit rarely) to refer to a white, blue-eyed counterpart to Night Furies. Both the design of the white dragon that Toothless will meet and [=DeBlois=] using "Light Fury" [[https://www.usatoday.com/story/life/movies/2018/06/05/how-train-your-dragon-3-new-photos-reveal-toothless-love/665961002/ in an interview]] has made Light Furies canon.

* TheOtherDarrin: When the cast was announced, Creator/TJMiller was meant to reprise his role as Tuffnut in the film. Justin Rupple replaces him on account of Miller's [[RoleEndingMisdemeanor controversial behaviour in 2018]].

* AdvertisedExtra: Eret son of Eret received this treatment. Despite Creator/KitHarington received his own hilarious promo video full of ActorAllusion, Eret's role is very minor and his biggest contribution to the plot is identifying the new BigBad Grimmel.

* ShortRunInPeru: The film was released weeks earlier ahead of its February 22 United States premiere in markets such as Australia (January 3), Norway and the Netherlands (January 11), and South Korea (January 30).

* WordOfGod: Director Dean [=DeBlois=] has revealed certain pieces of information about the film and characters.
** The main narrative of film takes place one year after ''Dragon 2'' with Hiccup still being an inexperienced Chief.
** The Light Fury is not another Night Fury, but a distinct relative of the species. Her ability to disappear through fireballs is caused by the fire heating her scales to become reflective of her surroundings.

* ExecutiveMeddling: According to [[https://www.thisisinsider.com/tj-miller-how-to-train-your-dragon-role-tuffnut-recast-2019-2 an Insider article]], Dean DeBlois had little say in T.J. Miller being recast.

* ChannelHop: This will be [=DreamWorks=]'s first film to be released by Creator/{{Universal}} after Comcast's acquisition of the studio. On that note, the first film was released by Paramount, and the second by Fox.

* AdvertisedExtra: Eret son of Eret received this treatment. Despite Creator/KitHarrington received his own hilarious promo video full of ActorAllusion, Eret's role is very minor and his biggest contribution to the plot is identifying the new BigBad Grimmel.