!!For the movie
* ActorAllusion: This isn't the only time Creator/JayBaruchel plays a [[Film/ShesOutOfMyLeague character that ends]] [[WesternAnimation/HowToTrainYourDragon his respective movie by flying away]].
* BoxOfficeBomb: Budget, $150 million sans marketing costs. Gross: $63 million domestic, $251 million worldwide. As noted below, however, it did better when available on home video.
* DawsonCasting: The 28-year old Jay Baruchel as the 20-year old Dave.
** Becky is played by Teresa Palmer, an Australian. Averted with Peyton Roi List, who is American.
** Jay Baruchel is Canadian. Averted with Jake Cherry, who is American.
* ShownTheirWork: As revealed in the behind-the-scenes material, the place where Dave has his secret lab (which is then turned into his apprentice training ground with Balthasar) is [[SinisterSubway an old subway turnaround]], and based explicitly (in architecture and design) on the City Hall IRT station.
* VindicatedByCable: The film recouped its losses when it was released on DVD and Blu-ray.
* WhatCouldHaveBeen: An earlier draft included an appearance by Chernabog himself in the climactic battle, though he'll be in the sequel [[DevelopmentHell if they get the chance]].
** The same earlier draft included Abigail in the climactic battle, as well as more emphasis on how magic works, different backgrounds for Balthazar and Horvath, and the title of Prime Merlinian being generational rather than once-in-a-lifetime.
!!For the webcomic
* WriteWhatYouKnow: Some of the ExpoSpeak makes it blatantly obvious that the author knows what she's talking about, such as when [[spoiler:Cooper gets bitten by a monster and Victoria instructs Cooper to ''not'' tell the doctors it was a random animal bite due to the complications of having to identify the breed of animal and getting rabies shots]].