Rachel Weisz did not appear in this third installment of "The Mummy" films, and instead, her character, Evy, was played by Maria Bello. There were differing accounts as to why this happened. According to director Rob Cohen, it was because Weisz refused to portray someone with a 21-year-old son, but according to Weisz herself, it was because she did not want to be away from her own son for five months while shooting in China. An additional reason was that Weisz simply did not like the script.
The crossbow traps in the tomb scene were based in reality. According to Chinese archaeologists, the excavation of the Terracotta Army is progressing so slowly, partly because the site is filled with similar traps.
The small device that triggers a trap by dropping a bronze marble from a dragon's mouth to a frog's mouth is inspired by an ancient instrument that could predict the direction of a coming earthquake. It is considered the first seismograph.
At the book reading, Eve is asked if her book series was actually based on her, and she answers, "Honestly, I can say she's a completely different person." This is, of course, an inside joke, alluding to the fact that Rachel Weisz, who played Eve in the first two films, was replaced by Maria Bello in this film.
The plot element of Jonathan Carnehan as the owner of a casino attacked by the bad guys was planned for The Mummy Returns (2001), but it was cut due to budget constraints and, brought back for this film.
Brendan Fraser, who plays Rick, was born in 1968. Maria Bello, who plays Evelyn, was born in 1967. Luke Ford, who plays their son, Alex, was born in 1981, making him thirteen years younger than Fraser and fourteen years younger than Bello.
This film marked the Hollywood debut for Chinese martial arts sensation Wu Jing (Jing Wu), who had a cameo as one of the assassins having a brief but furious battle with fellow Wu Shu expert Jet Li, at the beginning of the film.
Since Jet Li was only available for a part of the shoot, it was decided that the Emperor would be either a rotting mummy or encased in terracotta, in most of his scenes. In that way, Li could play the Emperor in the flesh, and the remainder of his role would be done by a CGI character.
Almost all of the technical crew from the Montreal filming location had custom made dog-tags with either "Foundation Soldier" or "Terracotta Warrior" and their names. The whole crew decided to do so after documentary filmmaker Todd Grossman and a few other crew members had some done for fun.
The airplane used to fly to Shangri-La, based on the Bristol Beaufighter, widely used by Britain and Australia in World War II, was reasonably expected to be available in China. Built as a two-seat fighter-bomber, it was never converted into a passenger-carrying aircraft, but such a conversion might have been theoretically possible. The aircraft shown is based on a real one, completed on April 2, 1945, and assigned to 93 Sqn based St. Kingaroy. It carried the code SK-N, and was nicknamed "Babs." On the rudder was a large gremlin, "pistol pakin' gremlin." She was crewed by WOFF L.W. Mutton (pilot) and FLTSGT C.G. Curthoys (navigator/radio operator/rear gunner.) On September 11, 1945, she suffered a forced landing at Neomfoor, after the starboard engine seized. She went into storage on September 2, 1946, and was struck off on August 8, 1949. 93 Sqn was formed on January 22, 1945 without an official name or motto, but unofficially became the "Green Ghost Squadron" with the unofficial motto "Spookus Sneakinus." In mid 1945, the squadron transferred to Labuan, an island off Borneowith, with the mission to disrupt Japanese shipping and airfields. In August 1945, the squadron was sent to destroy a Japanese oil tanker; the ship was sunk but turned out to be the 800-ton private yacht of the Rajah of Sarawak. The 93rd Squadron was disbanded on August 22, 1946.
Rob Cohen had always been very fascinated by Chinese culture and history, so when he was approached and heard the story was set in China, he immediately signed on as director. He insisted that the movie be filmed in China as much as possible, and made sure that ancient Chinese culture and art be depicted as accurately as possible.
The trivia items below may give away important plot points.
A slightly extended final fight between Rick, Alex and the Emperor was originally shot. After Rick (Brendan Fraser) manages to get the upper hand, the Emperor (Jet Li) changes back into a terracotta statue, which is subsequently broken into pieces by Rick. However, the pieces reassemble, forcing Rick and Alex (Luke Ford) to fight him together. The extended scene is included in the bonus material on the Blu-ray version.
Oded Fehr was asked to reprise his role as Ardeth Bay. Fehr declined because Imhotep was not to be in the film, and had felt that if there was no Imhotep, then Ardeth Bay had no point and reason to appear in the movie.