In the "Mortal Engines" book series, Hester is described as having lost most of her nose and one eye. Her scars are reduced for the film.

The original novel mentioned plastic idols of Walt Disney's Mickey and Pluto, "the animal-headed gods of lost America" in the London History Museum. This film, being made by Universal, instead has plastic idols of Despicable Me (2010)'s Minions.

Author Philip Reeve, writer of the novel on which the movie is based, published a blogpost on July 19th 2017 that principle photography had ended and he had been invited to the set back in May of the same year. He noted that he had been impressed by the actors and the sets, mentioning that "Most of it looked very much as I'd imagined, except for the bits which looked better."

The book that Katherine Valentine brings into the Museum at the beginning of the film is written by one Nimrod Pennyroyal, a character that would have become important in the sequels.

Jackson purchased the rights to the book in 2009, but the film languished for several years before being officially announced in 2016. Jackson brought on several members of his production teams from the Lord of the Rings and Hobbit film series, and filming took place from April to July 2017 in New Zealand.

Christian Rivers' first full feature film as a director. He previously directed a short and a section of an anthology, and was storyboard artist/special effects designer on Peter Jackson's Lord of the Rings and Hobbit films (who is also the producer of Mortal Engines).

As per usual in an adaptation of a young adult fantasy novel, the ages of the protagonists are all pushed up a bit. In the book, Tom and Hester are seventeen, Katherine Valentine is sixteen and Beavis Pod is eighteen.

Shipped to cinemas under the pseudonym "Squeeky Wheels".

When Hester's mother name is revealed to be Pandora Shaw, some viewers drew attention to the name of the software brand. This is actually a recurrent theme in the books, in which many characters have "ancient names" which are actually trademarks: Windolene Pye, Daz Gravy, Nutella Eisberg, Napster Varley, and Nabisco Shkin are all characters in the sequels. Others, like Chudleigh Pomeroy, are named after places in Devonshire, England, where author Philip Reeve lives.

Leon Reedijk, one of the Rustwater trader extras in the film, passed away before principal photography ended.

Based on the novel of the same name by Philip Reeve.

It is an USA-New Zealand co-production.

Cinematic debut of actress Leila George, who plays Katherine Valentine. George is the daughter of thespians Vincent D'Onofrio and Greta Scacchi.

The Mad Max (1979) movies are considered a possible influence behind the movie.

Patrick Malahide and Colin Salmon have both worked with actress Liz May Brice. Patrick Malahide had starred opposite Liz May Brice in Fortress 2 (2000) and Colin Salmon had starred opposite Liz May Brice in Resident Evil (2002). Both Colin Salmon and Liz May Brice had both starred in the ITV prison drama Bad Girls (1999) (TV Series). Colin Salmon played Dr. Rowan Dunlop in it's 8th and final season and Liz May Brice played Pat Kerrigan in Series 7 and 8.

In the "Mortal Engines" novel, London never was able to successfully attack the Shield Wall. Katherin Valentine gives MEDUSA new coordinates and it destroys itself and London in the process. In the film, MEDUSA fires at the Shield Wall twice and destroys a large portion of it before its engines are destroyed by Tom.

The title "Mortal Engines" comes from William Shakespeare's "Othello" (Act 3, Scene 3: "O you mortal engines, whose rude throats The immortal Jove's dead clamours counterfeit, farewell!"). It refers to the concept of Municipal Darwinism (turning cities into moving creatures that consume each other) being flawed, because the cities' engines are mortal and will eventually run down, and all the resources gone into keeping them going will have been used up for nothing.

In the "Mortal Engines" novel, Bevis Pod and Katherine Valentine are killed in the final battle. In the film, they survive.

In the "Mortal Engines" novel, London gets destroyed, forcing Hester and Tom to journey in search of another home. In the film, it remains intact.

The movie departs from the novel in some key aspects of the plot being treated as exposition: MEDUSA, the use London is planning for it, the feud between the Engineers and the Historians Guilds or Anna Fan being an Anti-Traction League spy are all big reveals in the book. Some, like the true nature of Shrike and Valentine being Hester's father, are not discussed until the sequels.

The movie portrays Lord Mayor Magnus Crome as an "old relic" clinging to a dead past and Valentine as the true villain of the story, even having him kill the Lord Mayor. In the book, Magnus Crome is the true antagonist, and Valentine is just a half willing pawn being strong armed by Crome. In the end, both die when MEDUSA malfunctions and destroys London.

Robert Sheehan plays Tom Natsworthy in this film, a character that's part of a ragtag team working to foil the plans of the antagonist, Valentine. He also played Simon in The Mortal Instruments: City of Bones, a character that's part of a ragtag team, also fighting against an antagonist named Valentine. The two films, and novels they are based on, are unrelated to each other, despite sharing the word 'Mortal' in them.

NFL star Michael Bennett (Philadelphia Eagles, Seattle Seahawks) makes a cameo early in the movie.