Wikipedia Wrote:

Fuji TV gave the ADV Films staff very few constraints when writing the new version, the only rules were "don't change the character names (including the ghosts); don't change the way the ghosts are slain (a reference to Japanese folklore) and, finally, don't change the core meaning of each episode".

The English dub deviates significantly from the original script. While preserving the basic plot structure and storyline, the new script revolved around topical pop-culture references, politically incorrect gags, and fourth wall breaking jokes about the original show's low animation quality, anime clichés, and poor lip-sync.

The English script was written by Steven Foster and Lucan Duran and allowed for ad-lib by the English voice actors. According to Foster, whoever showed up to the recording studio first for any given episode could improvise anything they wanted, those that came later had to build upon the tone and jokes established earlier.