In her autobiography "And Furthermore", Dame Judi Dench says that she never really understood what was going on in the movie, but she enjoyed the experience of making the movie, and she thought the sets were great.
The Purifier's line, "I've done unbelievable things in the name of a faith that was never my own", was not originally in the script. It was improvised by Linus Roache, and writer and director David Twohy kept it in the movie.
Toombs's (Nick Chinlund's) line regarding Crematoria, "If I owned this place and Hell, I'd rent this place out and live in Hell", is paraphrased from an infamous quote General Phil Sheridan made during post-Civil War Reconstruction, in which he said, "If I owned Hell and Texas, I would rent out Texas and live in Hell."
Vin Diesel wanted Dame Judi Dench to play Aereon, and went to great lengths to get her. A long-time fan of Dench, he had her dressing room filled with bouquets of flowers, and also advised her that they could not begin casting the movie until she agreed to accept the role.
The actors inside the Lensor costumes were skilled in body movement. Some were from Cirque Du Soleil.
David Twohy: After Riddick escapes from the Quasi-Deads, the statue and face of David Twohy can be seen on the Necromonger ship that's shot down by a team of Mercs, lead by Toombs.