In an interview with David Hayter, the voice of Solid Snake, he revealed that all the game's dialogue had to be rerecorded as the sound card in the GameCube was far better than the PlayStation's and cars could be heard on the original recordings.
At the time of the original game's release, it was not expected to get good reviews. For this reason most of the voice actors are credited under stage names. However the game was very successful and when all of those actors returned for this project, they used their real names. (Or most commonly known names) With the exception of Rob Paulsen who was not in the original game, the cast of main characters are voiced by the same actors. For the character of the Cyborg ninja, Rob was brought in as opposed to the previous game where the character was voiced by Greg Eagles who also provided the voice of the DARPA Chief.
Before the battle against the villain Psycho Mantis he comments on his ability to read minds and sees that in Snake's (your) free time you like to play Nintendo games and that you save frequently, he also names games that have been saved on you memory card (Legend of Zelda: The Wind Waker and Super Mario Sunshine) and then asks the player to place the controller flat on the ground and makes it move using his "power".
Although the English language script and dialogue remained mostly the same as first written in Metal Gear Solid (1998), a few lines and references were adjusted for better grammatical clarity, as well as lines referencing the Nintendo Gamecube's in-game controls (as opposed to the Sony Playstation version). Also, references made to Zanzibar in the original version of Metal Gear Solid were corrected to "Zanzibar Land", the ficticious nation that served as the setting for Metal Gear 2: Solid Snake (1990).
Ryûhei Kitamura created many of the game's cut scenes to look almost identical to the ones in Metal Gear Solid (1998). Hideo Kojima had him redo them, to make sure that they would all be in Kitamura's own style (thus keeping up the concept that this game would be a complete "re-imagination" of MGS).