Plans were made to adapt the other three books in the series, with director Stefen Fangmeier intending to film the second and third movie back-to-back. However, after negative reviews by both audience and critics, any ideas for sequels were dropped.
The film was advertised as "The First Chapter in the Inheritance Trilogy". At this time, the second story, "Eldest" had been published, but the third book was neither published nor named. The October after this film was released, book author Christopher Paolini announced that the final book would be split in two, making the Inheritance Trilogy the "Inheritance Cycle". (The final two books were named Brisingr and Inheritance.)
Christopher Paolini, author of the original novel, expressed his wishes to make a cameo appearance in the film, specifically a warrior who is beheaded in the battle of Farthen Dur. However, he was unable to due to the constraints of his European Book Tour.
As of 2015, this remains the first (and only) film directed by Stefen Fangmeier, who's mostly known for doing visual effects work on Terminator 2 (1991) and Jurassic Park (1993), and as the second unit director on Galaxy Quest (1999).
The final writing credits for the movie were not decided on until days before it was released, resulting in the posters crediting various combinations of Peter Buchman, Lawrence Konner, Mark Rosenthal and Jesse Wigutow for the screenplay. In the end, the WGA decided that Buchman alone should get the screenplay credit.
Emily Blunt was turned down for the part of Arya. However, it was during the casting process of this film that she caught the eye of a casting director from Fox, which led to her part in The Devil Wears Prada (2006).
Ágnes Bánfalvy, who played the Varden Woman originally had a larger role as the woman who asked Eragon to bless the baby. The scene was cut from the theatrical version, but were included in the film's deleted scenes credited as "Mother". Despite this, she can still be seen in the background with all the other Varden villagers.
The Princess is called Arya. In the HBO fantasy drama television series "Game of Thrones" Maisie Williams's character is called Arya Stark. Both "Eragon" and "Game of Thrones" are based on fantasy novels.
23 years earlier, Alun Armstrong starred in the 1983 fantasy film "Krull". The film was about a prince whom along with a fellowship of companions set out to rescue a princess from a fortress of alien invaders that have invaded that world.
The trivia item below may give away important plot points.
Eragon tries to save Brom with the incantation "Waisse heill!" This is an inside joke for language buffs. "Waes hael" ("Be well!") was an Old English drinking toast and source of the word "wassail," a kind of Christmas punch.