Random Trivia For This Title:
- The hesitation Toothless shows during the famous "touch" scene was actually an animation error. However, it looked so perfect that the animators chose to leave it in the film.
- Hiccup's exact age is never given in the film. However, in How to Train Your Dragon 2, which takes place five years after How to Train Your Dragon, Hiccup is said to be 20 years old. This would make him 15 years old in this film.
- Jay Baruchel co-starred with T.J. Miller in She's Out of My League, which was released just two weeks prior to How to Train Your Dragon. He would later also co-star with Christopher Mintz-Plasse and Jonah Hill in This Is the End.
- David Tennant, the narrator of the How To Train Your Dragon audio book series, provides the voice of Spitelout, though he is not credited. He also narrates some features on the film's website.
- Hiccup is left-handed, as demonstrated when he is writing in his journal/sketchbook.
- The hammer used by Stoick bears a strong resemblance to the Marvel comics version of the hammer Mjolnir, wielded by Marvel's Thor. The traditional mythological hammer of Thor looks much different.
- There is a drawing very closely resembling the Flux Capacitor from the Back to the Future (1985) movies on Hiccup's design board.
- The Night Fury dragon species was originally going to be be more wolf-like in appearance. Instead, a Dreamworks employee's computer screen saver of a black leopard inspired the film's creators to make Toothless more feline in appearance. The appearance and personality of Toothless was inspired by cats, dogs, and horses. The face also bears some resemblance to the giant salamander, the largest amphibian in the world. The shape of his face is also reported to have been based on the face of Stitch from Lilo & Stitch, also directed by Chris Sanders and Dean DeBlois.
- When Hiccup reads the Dragon Manual, the writings in it are actually in plain English cryptographed into runes. With little effort, you can read what Hiccup is saying, e.g. "Speed Unknown."
- Gobber has a total of fourteen different hand attachments throughout the film.
- In the book of "How to Train Your Dragon," Hiccup does not have a love interest. Furthermore, Toothless, the dragon in the book, is about the size of the Terrible Terror breed, and he is also green and red, not black. Toothless also got his name because when Hiccup first found him, he had no teeth. He grew one tooth, only to lose it shortly later. The producers decided, with the approval of author Cressida Cowell, that it would be more cinematic to make Toothless large enough to be ridden as a flying mount. As such, Toothless was completely redesigned as a rare Night Fury, a highly intelligent breed of dragon evolved for speed and stealth. His personal name, in the film, derives from Hiccup's observation about how his teeth are normally retracted into his jaws so they don't interfere with his fire breathing, which is typically projected as an explosive pulse.
- According to the audio commentary, when Hiccup, Astrid and Toothless are flying to Dragon Island and are surrounded by all the other dragons, one of the dragons is carrying Gloria, the hippo from Madagascar.