Converted Fanboy: James Marsters watched the anime to study his character. Afterwards, he started referring to the anime as "the coolest television cartoon in the last 50,000 years."
Creator's Apathy: Ramsey admitted in a 2016 apology letter to have gone into the film "as a businessman" and "not a fan" of Dragon Ball (whether this means he was a fan and just didn't care, or he was not a fan, period, isn't entirely clear).
Development Hell: Was reportedly stuck in this for a while. The movie was announced in 2002, the domain name "dragonballthemovie.com" had been registered by Fox back in 2003, but work didn't begin on it until 2007.
Akira Toriyama first showed what could be read as professionally polite disappointment over the film, stating that it should be taken as an "alternate universe" Dragon Ball. However, after the film was released and by the time of Dragon Ball Z: Battle of Gods, he had since clarified his stance: Despite offering advice to the crew on how to adapt the series, they had never listened to him, and thus the finished product was a disaster and something he could not see as anything Dragon Ball at all.
Ironically enough, the film that Dragon Ball fans love to hate was ultimately responsible for getting Akira Toriyama, a notoriously apathetic creator, to actually care about the franchise he started. Had he not been so leery of other people's treatment of his work after Evolution, he might never have taken charge of Battle of Gods after seeing the initial Darker and Edgier script treatment, and neither Dragon Ball Z: Resurrection ‘F’ nor Dragon Ball Super would ever have existed. Perhaps fans ought to be at least a bit thankful this movie exists.
Executive Meddling: Many of the changes were presumably added in due to Fox's meddling, especially considering their track record in other films. We'll never know how much was dictated to be there, and how much the writers came up with themselves though. One of the particularly nasty changes they wanted? To make Piccolo a Bishounen. James Marsters would not have this and demanded he'd be like the original.
Stillborn Franchise: Despite its obvious Sequel Hook, its reception among fans and critics as well as its box office intake assures that no sequels will be materializing anytime soon.
What Could Have Been: The original script was apparently a much more faithful adaptation of the series. But once it was out of the scriptmaker's hands, changes were made.
In an ironic twist on the whole matter, there are some sources which say that Wong, the director, added in elements that made the film more like the comic than the initial script. Which means... somehow... it could have actually been worse.
Though YMMV, the original script was found here and has alternate versions of the Namekians, Pilaf, Krillin, Puar, Suno, and Oolong, though it also adds a convoluted backstory involving an in-universe popular gaming franchise based on their real world battles with Piccolo.
Emmy Rossum was originally going to wear a short blue wig as Bulma, but it was ditched after a costume test as both she and the director hated how it looked. A pink wig was also said to have been tested.
While James Marsters was without a doubt one of the most praised things about the film, Ron Perlman was the original choice. and one can't help but Squee at that.