One of the scientific experts consulted for the making of the movie was Dr. David Stevenson of Cal-Tech. After talking to the producers, he thought of a scientifically possible way to send an unmanned probe to the core. His idea was published in the prestigious science journal Nature on 15 May 2003.
"Unobtainium" (sometimes spelled "Unobtanium") is a term used by science fiction fans (and some authors) for an extremely rare, not yet discovered, or physically impossible substance necessary for a given task.
At the University of British Columbia, Canada, an Earth and Ocean Science course (EOSC 310) uses this film as a learning tool by showing the film to students and then analyzing the bad science behind it. Ironically, at least one of UBC's professors was consulted during the shoots that were done in Vancouver.
In demonstrating the physics of what is happening, Aaron Eckhart's character uses a peach to make his point. Unfortunately none of the peaches brought to the set were suitable so an apple was painted and had a peachstone inserted into its middle.
Rat's demands changed three times during the progression from trailers to final film. In the original trailer, he demands "I want Star Trek (1966) tapes and Hot Pockets." In the recent trailer, he demands "I want SpongeBob SquarePants (1999) tapes and Hot Pockets." In the final film, he settles for "I want Xena: Warrior Princess (1995) tapes and Hot Pockets."
After the the space shuttle Columbia disintegrated during re-entry, trailers for the film were recalled to remove a brief scene of a space shuttle making an emergency landing (as this was felt to be to reminiscent of the recent event, but the producers stated that the sequence wouldn't be removed from the actual film.