To achieve the effect of weightlessness for the actors in the battle room, two rigs were invented for this movie, used to capture zero gravity scenes. First was a lollipop arm, which is like a counter-balance offering a full range of motion. The second innovation was a "people crane." It's a contraption, sort of like the lollipop arm, but put on air pucks so that the effects is like you are floating around in the air.
In the early 2000s, Jake Lloyd was one of the leading candidates to play Ender. Coincidentally, in 2000, when Lloyd appeared in a magazine ad campaign to promote library patronage, he was shown reading a copy of "Ender's Game".
Since the book's publication in 1985, Orson Scott Card claims he has fielded numerous options from Hollywood studios to produce a film, but he persistently refused in order to maintain the integrity of his vision. When he co-founded Fresco Pictures in 1996, Card decided to screen-write the film himself. However, the film remained unmade for another 17 years. When it was eventually made in 2013, Card's screenplay was not used. Card was given a producer credit on the film, though it was stated by the studio (after a boycott of the film was instigated by LGBT fans who oppose Card's anti-gay beliefs) that this was merely an honorary credit.
Special wheel harnesses that allowed free range in motion were fitted to actors, for filming of Battle Room scenes. Because these scenes are supposed to take place in a null gravity environment, the actors had to carefully choreograph their movements, to give the accurate illusion of floating.
The film was once developed at Warner Bros, intended to be directing vehicle for Wolfgang Petersen to be released around 2003. The studio acquired the rights in the mid-90s with Orson Scott Card began writing the screenplay in 1996.
Digital Domain, the VFX house behind ENDER'S GAME (and films like Iron Man 3 (2013) ) created a demo reel of the battle room before production that helped the producers successfully raise financing independently.
In May 2013 a group of LGBT fans launched a boycott campaign against the film due to anti-gay views and activities of the author of the novel, Orson Scott Card, who is also a producer of the film. The studio and several people involved with the film's production later released statements about the boycott, stating that they did not share Card's views and urged people to see the film anyway. Card, however, remained unapologetic.
During the game at the beginning of the movie, the ship piloted by Ender closely resembles the Millennium Falcon, the ship piloted by Harrison Ford's character in Star Wars: Episode IV - A New Hope (1977).
According to director Gavin Hood's commentary several planned scenes were cut due to financing problems when one of the investors backed out of the project. The same happened with planned CGI effects when one of the CGI studios working on the film went bankrupt during production.
The trivia items below may give away important plot points.
When Ender asks Mazer Rackham about his tattoos, he replies that it's his way to "speak for the dead". After the Final Battle and finding the Formic Queen Egg, Ender takes on the role and pseudonym of "Speaker For the Dead". He learns and understands the deceased and speaks upon their behalf, telling their story whether it be through a book or speech. His first subject is the Formic Race, but more specifically, the queens.
During the final battle, Ender's subordinates are sitting in front of transparent screens controlling the attack ships. Several times it can be seen that they are using a left-hand Razer Nostromo computer gaming keypad.