On August 24, 2009 (Hideo Kojima's birthday), thirteen years after the game's original release, an English translation patch was released for the PSX version. The translation encompasses every depiction of kanji in the whole game, and fixes some minor bugs and glitches. The link can be found in the related links section.
Policenauts was originally released for the NEC PC-98 (A Japanese only computer) in 1994.
When you come to BCCH to check Hojo's CD, you can look at the wall where Ishida was previously standing. There is a picture on that wall, which appears to be... the photo of Snatcher character cast! For those who don't know: both games were made by Hideo Kojima, the author of Metal Gear Solid.
Another nice reference to "Snatcher": in Karen's apartment, listen to the third CD... sounds familiar? :)
Saturn version of the game features some extras: a couple of flashback sequences for Jonathan were added, and during conversations, there are more close-ups on character faces.
Neither of the versions was released outside of Japan.