- Direct-to-Video: The film did not receive a theatrical release in Japan, and it took until mid-2015 for it to even get a DVD/Blu-ray release in the country.
- Image Source:
- Jossed: There was a popular belief going on for a while that Toothless would turn out to be a female dragon. However, if Valka's 20+ years of extensive dragon knowledge are to be trusted, the second film confirms that Toothless is in fact a male dragon. This is further confirmed in the third film, where Toothless falls in love with and ends up mating with a female dragon.
- Non-Singing Voice: When Valka joins in Stoick's song, that's Mary Jane Wells, not Cate Blanchett, even though Blanchett can actually sing pretty well as she has proven in a few interviews.
- So My Kids Can Watch: Apparently, at least part of the reason that Cate Blanchett agreed to voice Valka was because her children loved the first movie.
- Throw It In!:
- While watching Stoick and Valka argue, Gobber comments, "This is why I never got married. That and one other reason." Craig Ferguson ad-libbed the second part.
- Djimon Hounsou, Drago's voice actor, would do a series of vocal exercises before speaking as Drago, one of which was a loud, intimidating scream. The directors liked it so much they used it as Drago's dragon call for summoning his Bewilderbeast.
- What Could Have Been:
- From what can be gleaned from this interview, DeBlois had planned on giving the film two antagonists, likely as two balanced forces that would challenge Hiccup along the way. Drago would be as he appeared in the film: a great force that is a clear threat, and Valka as a more sympathetic villain whom Hiccup would, possibly, persuade to see his way of things.
- Drago was originally conceived as a Greater-Scope Villain that would be introduced in the second film and serve as the Big Bad for the third and final installment, but was moved up to the second after Valka's character was rewritten.
- DeBlois had originally wanted Gobber to be killed by the mind-controlled Toothless, but Guillermo del Toro suggested that Stoick be killed instead as it would service Hiccup's arc and have a stronger emotional impact.
- Fully animated scenes of Hiccup spending a bit longer time to wake Toothless up from the mind control were made, where he gets even closer and leans against Toothless' head while saying "I won't leave. I won't let you go." The creators might have thought that having Hiccup simply touch his head would be a more meaningful nod to how they first bonded, being the defining factor waking him up. That, and Drago allowing him that close without doing anything would be too unrealistic.
- Word of Gay: Subverted. That "one other reason" that Gobber never got married. Many raised an eyebrow and assumed that he's gay. Director Dean Dubois and Gobber's actor, Craig Ferguson, aren't denying it.
Trivia / How to Train Your Dragon 2