Kate Winslet was so keen to return in any capacity as either a "flashback or sim[ulation]" that she got her agents to get in contact with producers to specify her availability. However, it was the producers who turned down the opportunity for the sake of time and storyline constraints.
Like many other adaptations of Young Adult novel series (Harry Potter, Hunger Games, Twilight), the plan was to split the last book in the series ('Allegiant') into two films, with this movie basically covering the first half, and Ascendant covering the rest. However, due to negative reviews and a disappointing box office result, it, along with a TV series follow up, were subsequently cancelled.
Drones are supposed to be controlled with one's left hand. However, Chris is the only character who controls her drones with her right hand. This is due to Zoë Kravitz being left-handed.
Due to this film's underperformance in the box office, all talks for the sequel, Ascendant, was on hiatus. The sequel was supposed to be directed by Lee Toland Krieger, replacing Robert Schwentke. The project was later canceled. In July 2016, Lionsgate rather decided to release the sequel as a television film for a reduced budget. That film would spawn a TV series. Leading lady Shailene Woodley despised this decision and decided to stick with the project only if the sequel was a theatrical film. In February 2017, Starz and Lionsgate Television said that the TV film is under progress, resulting in the departure of Woodley from the project. After her leave, Starz later said that the television film is no longer a concern for them due to lack of interest from executives and the cast.
Despite the film's cliffhanger ending, there won't be a sequel to put a definitive ending to the story.