Trivia: When "Richard" starts to limp it wasn't planned, Harrison actually hurt a ligament in his knee shooting a promo for the movie, a promo that wasn't even part of the movie. He refused to receive treatment until filming was finished and ended up needing surgery.
Trivia: Director Andrew Davis had Harrison Ford start the film with a beard, and then shave it off, rather than using a disguise for Richard Kimble throughout the film.
Trivia: After his escape, it shows Harrison getting on a train marked with the name "Kimball" and then in the next shot, a helicopter flies over a hotel called "Harrison".
Trivia: In the courtroom when Richard Kimble is declared guilty, you can see a woman whispering to another woman behind Harrison Ford. This woman is Berniece Janssen, the mother of David Janssen, who portrayed Kimble in the original TV series of "The Fugitive."
Trivia: On the cinema, VHS and pre-2001 DVD release of this film, an engineer can be seen looking down at Harrison Ford when the latter is taking shelter from the runaway derailed locomotive. Producer Peter MacGregor-Scott discusses this on an added feature on the new transfer DVD and says that the man has been erased digitally from the film. The odd thing is that the engineer, seen in closeup, bears a remarkable resemblance to Peter MacGregor-Scott himself and might even be him, judging by the latter's joking about the unwanted character in the film.
Trivia: Before being cast as Richard Kimble, Harrison Ford had never seen an episode of the TV show "The Fugitive."
Trivia: Tommy Lee Jones' famous line "I don't care" was scripted, but only actually filmed after much debate, as he didn't like the line at all. According to screenwriter Jeb Stuart, he kept trying other lines instead. "After a while I just said, “Why don’t you just try, 'I don’t care?'" And once he did it, Andy Davis said, "That’s it. Wrap."
Trivia: The scene in which Dr Richard Kimble is first questioned by the Chicago PD was completely improvised. Harrison Ford did not know what the questions would be, which he preferred, as that would allow him to create a more genuine and emotional performance.
Trivia: Samuel Gerard's line "I don't care!" was ad-libbed by Tommy Lee Jones.
Answer: When Richard changes the diagnosis, the first thing he writes down is "AO" which is medical shorthand for aorta. Many people who have medical degrees and saw the movie speculate that Joel had an aortic tear. This would cause blood to flow into the chest cavity making it difficult to breathe and with the impact from the crash it could have caused the fatal injury. An aortic tear requires immediate surgery and by changing Joel's diagnosis, Kimble was able to save his life.