A number of pieces of the set, including those used for the rooftop chase, were sold to the production of Matrix (1999) at the end of shooting.
There were many deliberate anachronisms to give the viewer a feeling of confusion about the time period of the film.
New Line Cinema forced Alex Proyas to include the opening narration by Kiefer Sutherland, which gives away several plot reveals. Alex Proyas objected to it, saying it was unnecessary, and he subsequently removed the narration from his director's cut.
Alex Proyas got the idea for the buildings changing and growing while the crew was moving pieces of the set around during filming of The Crow (1994).
An over-sized version of Dr. Schreber's syringe (roughly a yard long) was built for the close up shots of the needle being extended so that its surface details could be seen clearly.