The Wachowskis were keen that all involved understood the thematic background of the film. One of the requirements for actors on the film was that they had to be able to explain The Matrix. The book used to conceal disks early in the film, Simulacra and Simulation, a 1981 work by the French philosopher Jean Baudrillard, was required reading for most of the principal cast and crew. Reeves stated that the Wachowski brothers had him read Simulacra and Simulation, Out of Control, and Evolutionary Psychology even before they opened up the script, and eventually he was able to explain all the philosophical nuances involved. Moss commented that she had difficulty with this process.
The directors had also long been admirers of Hong Kong action cinema, so they decided to hire the Chinese director and martial arts choreographer Yuen Woo-ping to work on fight scenes. To prepare for the wire fu, the actors were required to train intensively for months. The Wachowskis first scheduled four months for training. Yuen was optimistic but then began to worry when he realized how unfit the actors were
Yuen let their body style develop and then worked with each actor’s strength. He built on Reeves’ diligence, Fishburne’s resilience, Weaving’s precision, and Moss’s feminine grace. Yuen designed Moss’ moves to suit her deftness and lightness. Prior to the pre-production, Reeves had suffered two-level fusion of his cervical spine and his legs had been becoming paralyzed, so he had undergone a neck surgery. He was still
recovering by the time of pre-production, but he insisted on training, so Yuen let him practice punches and lighter moves. Reeves trained hard and even requested training on days off. However, the surgery still made him unable to kick for two out of four months of training. As a result, Reeves did not kick much in the film. Weaving had to undergo surgery on his hip after suffering an injury during training.